Cyclohexene derivative having alkenyl, liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal compound selected from a group of compounds represented by formula (a): 
                         
wherein Ra and Rb are each independently hydrogen, alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, provided that in the alkyl, —CH 2 — may be replaced by —O—, but plural —O— are not adjacent to each other, and hydrogen may be replaced by fluorine; ring A 1  and ring A 2  are each independently trans-1,4-cyclohexylene or 1,4-phenylene, provided that one or two hydrogens of the 1,4-phenylene may be replaced by halogen, and in a 6-membered ring of these groups, one —CH 2 — or two —CH 2 — that are not adjacent to each other may be replaced by —O—, and one or two —CH═ may be replaced by —N═; Z 1  and Z 2  are each independently a single bond, —(CH 2 ) 2 —, —(CH 2 ) 4 —, —CH═CH—, —C≡—, —CH 2 O—, —OCH 2 —, —COO—, —OCO— or —OCF 2 —; l and m are each independently 0, 1 or 2, provided that l+m is 0, 1, 2 or 3; and n is an integer of from 0 to 6, provided that in —(CH 2 ) n —, —CH 2 — may be replaced by —O—, but plural —O— are not adjacent to each other, and hydrogen may be replaced by fluorine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to JapanesePatent Application No. JP 2006-242156, filed Sep. 6, 2006, whichapplication is expressly incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal compound, a liquid crystalcomposition and a liquid crystal display device. More specifically, itrelates to a difluorobenzene derivative having alkenyl and cyclohexenyl,a liquid crystal composition having a nematic phase and including thecompound, and a liquid crystal display device including the composition.

2. Related Art

A liquid crystal display device, which is represented by a liquidcrystal display panel and a liquid crystal display module, utilizesoptical anisotropy and dielectric anisotropy of a liquid crystalcompound (which is a generic term for a compound having a liquid crystalphase, such as a nematic phase, a smectic phase and so forth, and alsofor a compound having no liquid crystal phase but being useful as acomponent of a composition). As an operation mode of a liquid crystaldisplay device, various modes have been known, such as a phase change(PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN)mode, a bistable twisted nematic (BTN) mode, an electrically controlledbirefringence (ECB) mode, an optically compensated bend (OCB) mode, anin-plane switching (IPS) mode, a vertical alignment (VA) mode, and soforth.

Among these modes, an ECB mode, an IPS mode, a VA mode and so forth areoperation modes utilizing vertical orientation property of a liquidcrystal molecule, and in particular, it has been known that an IPS modeand a VA mode can eliminate a narrow viewing angle, which is a defect ofthe conventional modes, such as a TN mode and an STN mode.

As a component of a liquid crystal composition having a negativedielectric anisotropy, which can be used in a liquid crystal displaydevice of these modes, various kinds of liquid crystal compounds, inwhich hydrogen on a benzene ring is replaced by fluorine, have beeninvestigated (as described, for example, in JP H02-4725 A/1990, JP2000-53602 A, JP H10-237075 A/1998, JP H02-4723 A/1990, JP 2002-193853A, WO 89/08633, WO 89/08687 and EP 1333017).

For example, a compound (A), in which hydrogen on a benzene ring isreplaced by fluorine, is studied in JP H02-4725 A/1990, but the compoundhas a small optical anisotropy.

A compound (B), in which hydrogen on a benzene ring is replaced byfluorine, having alkenyl is studied in JP 2000-53602 A, but the compounddoes not have a sufficiently large optical anisotropy.

A compound (C), in which hydrogen on a benzene ring is replaced byfluorine, having cyclohexenylene and oxabicyclopentane is studied in JPH10-237075 A/1998, but the mesophase range where the compound exhibitsliquid crystallinity is significantly narrow, and a compositionincluding the compound does not show a high clearing point.

A compound (D) and a compound (E), in which hydrogen on a benzene ringis replaced by fluorine, having cyclohexenylene have been reported, forexample, in JP H02-4723 A/1990 and JP 2002-193853 A, but the compoundsexhibit poor compatibility with other liquid crystal compounds in a lowtemperature range.

WO 89/08633, WO 89/08687 and EP 1333017 report compounds, in which thehydrogen on a benzene ring is replaced by fluorine, havingcyclohexenylene, are disclosed as an intermediate, but the compounds areutilized only as a raw material or an intermediate, and furthermore, nocompound having both alkenyl and cyclohexenylene simultaneously has notbeen studied.

Accordingly, a liquid crystal display device having an operation mode,such as an IPS mode or a VA mode, still has problems as a display devicecompared to CRT, and, for example, needs to be improved in response timeand contrast and decreased in driving voltage.

The display device driven in an IPS mode or a VA mode mainly includes aliquid crystal composition having a negative dielectric anisotropy, andin order to improve the aforementioned properties, a liquid crystalcompound included in the liquid crystal composition necessarily has thefollowing properties (1) to (8):

(1) The compound is chemically stable and physically stable;

(2) The compound has a high clearing point (transition temperature froma liquid crystal phase to an isotropic phase);

(3) The compound has a low minimum temperature of a liquid crystal phase(such as a nematic phase and a smectic phase), and particularly has alow minimum temperature of a nematic phase;

(4) The compound has a low viscosity;

(5) The compound has a suitable optical anisotropy;

(6) The compound has a suitable negative dielectric anisotropy;

(7) The compound has a suitable elastic constant K₃₃ (K₃₃: bend elasticconstant); and

(8) The compound is excellent in compatibility with other liquid crystalcompounds.

In the case where a composition including a liquid crystal compound thatis chemically and physically stable as in (1) is used in a displaydevice, the voltage holding ratio can be increased.

In the case where a composition including a liquid crystal compoundhaving a high clearing point or a low minimum temperature of a liquidcrystal phase as in (2) and (3) is used, a temperature range of thenematic phase can be enhanced, and a display device can be used in awide temperature range.

In the case where a composition including a compound having a smallviscosity as in (4) or a large elastic constant K₃₃ as in (7) is used ina display device, the response time can be improved. In the case where acomposition including a compound having a suitable optical anisotropy asin (5) is used in a display device, the contrast of the display devicecan be improved. Liquid crystal compounds having optical anisotropyvarying over a wide range are necessary depending on design of a displaydevice. In recent years, a method has been studied in which the cellthickness is decreased to improve the response time and, accordingly, acomposition having a large optical anisotropy is desired.

Furthermore, in the case where a liquid crystal compound has a largenegative dielectric anisotropy, a liquid crystal composition includingthe compound can have a low threshold voltage, and accordingly, adisplay device using a composition including a suitable negativedielectric anisotropy as in (6) can have a low driving voltage and asmall electric power consumption. Furthermore, in the case where acomposition including a compound having a small elastic constant K₃₃ asin (7) is used in a display device, the display device can have a lowdriving voltage and a small electric power consumption.

A liquid crystal compound is generally used as a composition by mixingwith other various liquid crystal compounds for obtaining propertiesthat cannot be exhibited with a single compound. Accordingly, a liquidcrystal compound used in a display device preferably has goodcompatibility with other liquid crystal compounds as in (8).Furthermore, a display device may be used over a wide temperature rangeincluding a temperature below freezing point, and therefore, thecompound preferably exhibits good compatibility in low temperatureranges.

SUMMARY OF THE INVENTION

The invention relates to a liquid crystal compound selected from a groupof compounds represented by formula (a):

wherein Ra and Rb are each independently hydrogen, alkyl having 1 to 10carbons or alkenyl having 2 to 10 carbons, provided that in the alkyl,—CH₂— may be replaced by —O—, but plural —O— are not adjacent to eachother, and hydrogen may be replaced by fluorine; ring A¹ and ring A² areeach independently trans-1,4-cyclohexylene or 1,4-phenylene, providedthat one or two hydrogens of the 1,4-phenylene may be replaced byhalogen, and in a 6-membered ring of these groups, one —CH₂— or two—CH₂— that are not adjacent to each other may be replaced by —O—, andone or two —CH═ may be replaced by —N═; Z¹ and Z² are each independentlya single bond, —(CH₂)₂—, —(CH₂)₄—, —CH═CH—, —C≡C—, —CH₂O—, —OCH₂—,—COO—, —OCO— or —OCF₂—; l, m and n are each independently 0, 1 or 2,provided that l+m+n is 0, 1, 2 or 3; and n is an integer of from 0 to 6,provided that in —(CH₂)_(n)—, —CH₂— may be replaced by —O—, but plural—O— are not adjacent to each other, and hydrogen may be replaced byfluorine.

The invention also relates to a liquid crystal composition that includesthe liquid crystal compound and so forth.

The invention also relates to a liquid crystal display device thatincludes the liquid crystal composition and so forth.

DETAILED DESCRIPTION OF THE INVENTION

One of the advantages of the invention is to provide a liquid crystalcompound that has stability to heat, light and so forth, exhibits anematic phase in a wide temperature range, has a small viscosity, alarge optical anisotropy and suitable elastic constants K₃₃ (K₃₃: bendelastic constant), and has a suitable negative dielectric anisotropy andexcellent compatibility with other liquid crystal compounds. Thecompounds of the invention exhibit a maximum temperature of a nematicphase that is not decreased, and has a tendency that the opticalanisotropy is increased without an increase of the viscosity.

Another advantage of the invention is to provide a liquid crystalcomposition that has stability to heat, light and so forth, has a lowviscosity, has a suitable negative dielectric anisotropy, has a lowthreshold voltage, has a high maximum temperature of a nematic phase(high phase transition temperature from a nematic phase to an isotropicphase), and has a low minimum temperature of a nematic phase. Inparticular, the liquid crystal composition of the invention has a largeoptical anisotropy and is effective as part of a device that is requiredto have a large optical anisotropy.

Still another advantage of the invention is to provide a liquid crystaldisplay device including the composition that has a short response time,has a small electric power consumption and a low driving voltage, has alarge contrast, and can be used over a wide temperature range.Accordingly, the liquid crystal display device can be used as a liquidcrystal display device of a display mode, such as a PC mode, a TN mode,an STN mode, an ECB mode, an OCB mode, an IPS mode, a VA mode and soforth, and in particular, it can be preferably used as a liquid crystaldisplay device of an IPS mode and a VA mode.

It has been found that a liquid crystal compound having a particularstructure, in which the structure has a alkenyl and cyclohexenylene, andfurther has a phenylene in which hydrogen on a benzene ring is replacedby fluorine, has stability to heat, light and so forth, exhibits anematic phase in a wide temperature range, has a small viscosity, alarge optical anisotropy and a suitable elastic constant K₃₃, and has asuitable negative dielectric anisotropy and excellent compatibility withother liquid crystal compounds. A liquid crystal composition includingthe compound has also been found that has stability to heat, light andso forth, has a low viscosity, has a large optical anisotropy, asuitable elastic constant K₃₃ and a suitable negative dielectricanisotropy, has a low threshold voltage, has a high maximum temperatureof a nematic phase, and has a low minimum temperature of a nematicphase, and a liquid crystal display device including the composition hasa short response time, has a small electric power consumption and a lowdriving voltage, has a large contrast, and can be used over a widetemperature range.

The invention will be described in detail below. In the followingdescription, all the amounts of the compounds expressed in terms ofpercentage mean weight percentage (% by weight) based on the totalweight of the composition.

The invention includes:

1. A liquid crystal compound selected from a group of compoundsrepresented by formula (a):

wherein Ra and Rb are each independently hydrogen, alkyl having 1 to 10carbons or alkenyl having 2 to 10 carbons, provided that in the alkyl,—CH₂— may be replaced by —O—, but plural —O— are not adjacent to eachother, and hydrogen may be replaced by fluorine; ring A¹ and ring A² areeach independently trans-1,4-cyclohexylene or 1,4-phenylene, providedthat one or two hydrogens of the 1,4-phenylene may be replaced byhalogen, and in a 6-membered ring of these groups, one —CH₂— or two—CH₂— that are not adjacent to each other may be replaced by —O—, andone or two —CH═ may be replaced by —N═; Z¹ and Z² are each independentlya single bond, —(CH₂)₂—, —(CH₂)₄—, —CH═CH—, —C≡—, —CH₂O—, —OCH₂—, —COO—,—OCO— or —OCF₂—; l and m are each independently 0, 1 or 2, provided thatl+m is 0, 1, 2 or 3; and n is an integer of from 0 to 6, provided thatin —(CH₂)_(n)—, —CH₂— may be replaced by —O—, but plural —O— are notadjacent to each other, and hydrogen may be replaced by fluorine.

2. The liquid crystal compound according to item 1, wherein ring A¹,ring A² and ring A³ are each independently trans-1,4-cyclohexylene or1,4-phenylene; Z¹ and Z² are each a single bond; and l+m is 0 or 1; andn is an integer of from 0 to 6.

3. The liquid crystal compound according to item 2, wherein Ra ishydrogen or alkyl having 1 to 10 carbons; and Rb is alkoxy having 1 to 9carbons.

4. The liquid crystal compound according to item 3, wherein l+m is 1.

5. A liquid crystal composition including at least one compound selectedfrom a group of the compounds according to any one of items 1 to 4.

6. A liquid crystal composition having a negative dielectric anisotropyand including two components, wherein the first component is at leastone compound selected from a group of the compounds according to any oneof items 1 to 4, and the second component is at least one compoundselected from a group of compounds represented by formulae (e-1), (e-2)and (e-3):

wherein Ra₁₁ and Rb₁₁ are each independently alkyl having 1 to 10carbons, provided that in the alkyl, —CH₂— that are not adjacent to eachother may be replaced by —O—, —(CH₂)₂— that are not adjacent to eachother may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴ are eachindependently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and Z¹¹, Z¹² and Z¹³are each independently a single bond, —CH₂—CH₂—, —CH═CH—, —C≡—, —COO— or—CH₂O—.

7. A liquid crystal composition having a negative dielectric anisotropyand including two components, wherein the first component is at leastone compound selected from a group of the compounds according to item 3,and the second component is at least one compound selected from a groupof compounds represented by formulae (e-1), (e-2) and (e-3) according toitem 6.

8. The liquid crystal composition according to item 7, wherein the ratioof the first component is from approximately 30% to approximately 85% byweight, and the ratio of the second component is from approximately 15%to approximately 70% by weight, based on the total weight of the liquidcrystal composition.

9. The liquid crystal composition according to items 6 or 7, wherein theliquid crystal composition further includes, in addition to the firstcomponent and the second component, at least one compound selected froma group of compounds represented by formulae (g-1), (g-2), (g-3) and(g-4) as a third component:

wherein Ra₂₁ and Rb₂₁ are each independently hydrogen or alkyl having 1to 10 carbons, provided that in the alkyl, —CH₂— that are not adjacentto each other may be replaced by —O—, —(CH₂)₂— that are not adjacent toeach other may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A²¹, ring A²² and ring A²³ are each independentlytrans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; Z²¹, Z²² and Z²³ areeach independently a single bond, —CH₂—CH₂—, —CH═CH—, —C≡C—, —OCF₂—,—CF₂O—, —OCF₂CH₂CH₂—, —CH₂CH₂CF₂O—, —COO—, —OCO—, —OCH₂— or —CH₂O—; Y¹,Y², Y³ and Y⁴ are each independently fluorine or chlorine; and q, r ands are each independently 0, 1 or 2, provided that q+r+s is 1, 2 or 3,and t is 0, 1 or 2.

10. The liquid crystal composition according to item 9, wherein thethird component is at least one compound selected from a group ofcompounds represented by formulae (h-1), (h-2), (h-3), (h-4) and (h-5):

wherein Ra₂₂ is linear alkyl having 1 to 8 carbons or linear alkenylhaving 2 to 8 carbons; Rb₂₂ is linear alkyl having 1 to 8 carbons,linear alkenyl having 2 to 8 carbons or alkoxy having 1 to 7 carbons;Z²⁴ is a single bond or —CH₂CH₂—; and both Y¹ and Y² are fluorine, orone of Y¹ and Y² is fluorine, and the other is chlorine.

11. A liquid crystal composition having a negative dielectric anisotropyand including three components, wherein the first component is at leastone compound selected from a group of the compounds according to items3, the second component is at least one compound selected from a groupof compounds represented by formulae (e-1), (e-2) and (e-3) according toitem 6, and the third component is at least one compound selected from agroup of compounds represented by formulae (h-1), (h-2), (h-3), (h-4)and (h-5) according to item 10.

12. The liquid crystal composition according to any one of items 9 to11, wherein the ratio of the first component is from approximately 10%to approximately 80% by weight, the ratio of the second component isfrom approximately 10% to approximately 80% by weight, and the ratio ofthe third component is from approximately 10% to approximately 80% byweight, based on the total weight of the liquid crystal composition.

13. The liquid crystal composition according to any one of items 5 to12, wherein the liquid crystal composition further includes at least oneantioxidant and/or an ultraviolet light absorbent.

14. The liquid crystal composition according to item 13, wherein theliquid crystal composition further includes an antioxidant representedby formula (I):

wherein w is an integer of 1 to 15.

15. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 5 to 14.

16. The liquid crystal display device according to item 15, wherein theliquid crystal display device has an operation mode of a VA mode or anIPS mode, and has a driving mode of an active matrix mode.

Liquid Crystal Compound (a)

The liquid crystal compound of the invention has a structure representedby formula (a) below. Hereinafter, the compound may be referred to as aliquid crystal compound (a).

In formula (a), Ra and Rb are each independently hydrogen, alkyl having1 to 10 carbons or alkenyl having 2 to 10 carbons. In the alkyl, —CH₂—may be replaced by —O—, but plural —O— are not adjacent to each other,and hydrogen may be replaced by fluorine.

In formula (a), ring A¹ and ring A² are each independentlytrans-1,4-cyclohexylene or 1,4-phenylene. One or two hydrogens of the1,4-phenylene may be replaced by halogen. In a 6-membered ring of thesegroups, one —CH₂— or two —CH₂— that are not adjacent to each other maybe replaced by —O—, and one or two —CH═ may be replaced by —N═.

In formula (a), Z¹ and Z² are each independently a single bond,—(CH₂)₂—, —(CH₂)₄—, —CH═CH—, —C≡—, —CH₂O—, —OCH₂—, —COO—, —OCO— or—OCF₂—.

In formula (a), l, m and n are each independently 0, 1 or 2, providedthat l+m is 0, 1, 2 or 3.

In formula (a), n is an integer of from 0 to 6, provided that in—(CH₂)_(n)—, —CH₂— may be replaced by —O—, but plural —O— are notadjacent to each other, and hydrogen may be replaced by fluorine.

The compound (a) has alkenyl, cyclohexenylene and 1,4-phenylene, inwhich hydrogens on the 2- and 3-positions are replaced by fluorine.Owing to the structure, the compound exhibits a nematic phase over awide temperature range, has a small viscosity, a large opticalanisotropy, a suitable elastic constant K₃₃, a suitable negativedielectric anisotropy and excellent compatibility with other liquidcrystal compounds. In particular, it exhibits a maximum temperature of anematic phase that is not decreased, and has a large optical anisotropywithout increase of the viscosity.

In formula (a), Ra and Rb are the groups mentioned above, and in thecase where the alkyl is CH₃(CH₂)₃—, for example, it may be CH₃(CH₂)₂O—,CH₃—O—(CH₂)₂—, CH₃—O—CH₂—O—, H₂C═CH—(CH₂)₂—, CH₃—CH═CH—CH₂—, orCH₃—CH═CH—O—, which are obtained by replacing —CH₂— by —O— or replacing—(CH₂)₂— by —CH═CH—.

However, taking the stability of the compound into consideration, agroup having plural oxygens adjacent to each other, such asCH₃—O—O—CH₂—, and a group having plural —CH═CH— adjacent to each other,such as CH₃—CH═CH—CH═CH—, are not preferred.

Specific examples of Ra and Rb include hydrogen, alkyl, alkoxy,alkoxyalkyl, alkoxyalkoxy, alkenyl, alkenyloxy, alkenyloxyalkyl andalkoxyalkenyl.

In these groups, one or more hydrogen may be replaced by fluorine.

In these groups, the chain of carbon-carbon bond in the groups ispreferably a linear chain. In the case where the chain of carbon-carbonbond is a linear chain, the temperature range of the liquid crystalphase can be enhanced, and the viscosity can be decreased. In the casewhere one of Ra and Rb is an optically active group, the compound isuseful as a chiral dopant, and the addition of the compound to a liquidcrystal composition can prevent formation of a reverse twisted domaingenerated in a liquid crystal display device.

The alkenyl in the groups has a preferred steric configuration of—CH═CH— depending on the position of the double bond in alkenyl.

In alkenyl having a double bond at an odd number position, such as—CH—CHCH₃, —CH═CHC₂H₅, —CH═CHC₃H₇, —CH═CHC₄H₉, —C₂H₄CH═CHCH₃ and—C₂H₄CH═CHC₂H₅, the steric configuration is preferably a transconfiguration.

In alkenyl having a double bond at an even number position, such as—CH₂CH═CHCH₃, —CH₂CH═CHC₂H₅ and —CH₂CH═CHC₃H₇, the steric configurationis preferably a cis configuration. An alkenyl compound having thepreferred steric configuration has a wide temperature range of a liquidcrystal phase, a large elastic constant ratio K₃₃/K₁₁ (K₃₃: bend elasticconstant, K₁₁: splay elastic constant) and a small viscosity. By addingthe liquid crystal compound to a liquid crystal composition, the liquidcrystal composition has a high maximum temperature (T_(NI)) of a nematicphase.

Specific examples of the alkyl include —CH₃, —C₂H₅, —C₃H₇, —C₄H₉,—C₅H₁₁, —C₆H₁₃, —C₇H₁₅, —C₈H₁₇, —C₉H₁₅ and —C₁₀H₂₁.

Specific examples of the alkoxy include —OCH₃, —OC₂H₅, —OC₃H₇, —OC₄H₉,—OC₅H₁₁, —OC₆H₁₃, —OC₇H₁₅, —OC₈H₁₇ and —OC₉H₁₉.

Specific examples of the alkoxyalkyl include —CH₂OCH₃, —CH₂OC₂H₅,—CH₂OC₃H₇, —(CH₂)₂OCH₃, —(CH₂)₂OC₂H₅, —(CH₂)₂OC₃H₇, —(CH₂)₃OCH₃,—(CH₂)₄OCH₃ and —(CH₂)₅OCH₃.

Specific examples of the alkenyl include —CH═CH₂, —CH═CHCH₃, —CH₂CH═CH₂,—CH═CHC₂H₅, —CH₂CH═CHCH₃, —(CH₂)₂CH═CH₂, —CH═CHC₃H₇, —CH₂CH═CHC₂H₅,—(CH₂)₂CH═CHCH₃ and —(CH₂)₃CH═CH₂.

Specific examples of the alkenyloxy include —OCH₂CH═CH₂, —OCH₂CH═CHCH₃,—O(CH₂)₂CH═CH₂ and —OCH₂CH═CHC₂H₅.

Specific examples of alkyl, in which hydrogen is replaced by halogen,include —CH₂F, —CHF₂, —CF₃, —(CH₂)₂F, —CF₂CH₂F, —CF₂CHF₂, —CH₂CF₃,—CF₂CF₃, —(CH₂)₃F, —(CF₂)₂CF₃, —CF₂CHFCF₃ and —CHFCF₂CF₃.

Specific examples of alkoxy, in which hydrogen is replaced by halogen,include —OCF₃, —OCHF₂, —OCH₂F, —OCF₂CF₃, —OCF₂CHF₂, —OCF₂CH₂F,—OCF₂CF₂CF₃, —OCF₂CHFCF₃ and —OCHFCF₂CF₃.

Specific examples of alkenyl, in which hydrogen is replaced by halogen,include —CH═CHF, —CH═CF₂, —CF═CHF, —CH═CHCH₂F, —CH═CHCF₃ and—(CH₂)₂CH═CF₂.

Ra is a group connected to —CH═CH—, and in the case where Ra is a group,such as CH₃—CH═CH—, such a structure as CH₃—CH═CH—CH═CH— is provided.The structure having plural —CH═CH— adjacent to each other is notpreferred since it is unstable to light.

Among the specific examples for Ra, preferred examples thereof includehydrogen, —CH₃, —C₂H₅, —C₃H₇, —C₄H₉, —C₅H₁₁, —OCH₃, —OC₂H₅, —OC₃H₇,—OC₄H₉, —OC₅H₁₁, —CH₂OCH₃, —(CH₂)₂OCH₃, —(CH₂)₃OCH₃, —CH₂CH═CH₂,—CH₂CH═CHCH₃, —(CH₂)₂CH═CH₂, —CH₂CH═CHC₂H₅, —(CH₂)₂CH═CHCH₃,—(CH₂)₃CH═CH₂, —(CH₂)₃CH═CHCH₃, —(CH₂)₃CH═CHC₂H₅, —(CH₂)₃CH═CHC₃H₇,—OCH₂CH═CH₂, —OCH₂CH═CHCH₃, —OCH₂CH═CHC₂H₅, —CF₃, —CHF₂, —CH₂F, —OCF₃,—OCHF₂, —OCH₂F, —OCF₂CF₃, —OCF₂CHF₂, —OCF₂CH₂F, —OCF₂CF₂CF₃, —OCF₂CHFCF₃and —OCHFCF₂CF₃, and from the standpoint of excellent light resistanceand heat resistance, hydrogen, —CH₃, —C₂H₅, —C₃H₇ are more preferred.

Among the specific examples for Rb, preferred examples thereof includehydrogen, —CH₃, —C₂H₅, —C₃H₇, —C₄H₉, —C₅H₁₁, —OCH₃, —OC₂H₅, —OC₃H₇,—OC₄H₉, —OC₅H₁₁, —CH₂OCH₃, —(CH₂)₂OCH₃, —(CH₂)₃OCH₃, —CH═CH₂, —CH═CHCH₃,—CH₂CH═CH₂, —CH═CHC₂H₅, —CH₂CH═CHCH₃, —(CH₂)₂CH═CH₂, —CH═CHC₃H₇,—CH₂CH═CHC₂H₅, —(CH₂)₂CH═CHCH₃, —(CH₂)₃CH═CH₂, —OCH₂CH═CH₂,—OCH₂CH═CHCH₃, —OCH₂CH═CHC₂H₅, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂,—OCH₂F, —OCF₂CF₃, —OCF₂CHF₂, —OCF₂CH₂F, —OCF₂CF₂CF₃, —OCF₂CHFCF₃ and—OCHFCF₂CF₃. From the standpoint of chemical stability and a negativelylarge dielectric anisotropy, —OCH₃, —OC₂H₅, —OC₃H₇, —OC₄H₉ and —OC₅H₁₁are more preferred, and from the standpoint of excellent compatibilitywith other liquid crystal compounds at a low temperature, hydrogen,—CH₃, —C₂H₅, —C₃H₇, —C₄H₉, —C₅H₁₁, —CH₂CH═CHCH₃, —(CH₂)₂CH═CH₂,—CH₂CH═CHC₂H₅ and —(CH₂)₂CH═CHCH₃, —(CH₂)₃CH═CH₂ are more preferred.

Ring A¹ and ring A² are each independently 1,4-cyclohexylene or1,4-phenylene. One or two hydrogens of the 1,4-phenylene may be replacedby halogen. In these groups, one —CH₂— or two —CH₂— that are notadjacent to each other may be replaced by —O—, and one or two —CH═ maybe replaced by —N═.

Preferred examples of ring A¹ and ring A² includetrans-1,4-cyclohexylene, trans-1,3-dioxane-2,5-diyl,trans-tetrahydropyran-2,5-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,5-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyridine-2,5-diyl, 6-fluoropyridine-2,5-diyl or pyridazine-2,5-diyl.

Among these, from the standpoint of chemical stability, a high clearingpoint and a small viscosity, trans-1,4-cyclohexylene and 1,4-phenyleneare more preferred. From the standpoint of a negatively high dielectricanisotropy, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene and2,3-difluoro-1,4-phenylene are preferred. From the standpoint of a largeoptical anisotropy, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,5-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyridine-2,5-diyl, 6-fluoropyridine-2,5-diyl or pyridazine-2,5-diyl arepreferred. From the standpoint of excellent compatibility with otherliquid crystal compounds, trans-tetrahydropyran-2,5-diyl is morepreferred.

In particular, in the case where at least two rings among the rings areeach trans-1,4-cyclohexylene, the compound has a small viscosity, and byadding the compound to a liquid crystal composition, the composition hasa high maximum temperature (T_(NI)) of a nematic phase.

In the case where at least one ring among the rings is 1,4-phenylene,there is such a tendency that the compound has a large opticalanisotropy (Δn), and the orientation order parameter can be increased.

In the case where at least two rings among the rings are each1,4-phenylene, the compound has a large optical anisotropy.

Z1 and Z2 are each independently a single bond, —(CH₂)₂—, —(CH₂)₄—,—CH═CH—, —C≡C—, —CH₂O—, —OCH₂—, —COO—, —OCO— or —OCF₂—.

Z¹ and Z² are preferably a single bond or —(CH₂)₂— from the standpointof stability of the compound, is preferably —(CH₂)₂—, —(CH₂)₄—, —CH═CH—,—CH₂O—, —OCH₂—, —COO—, —OCO— or —OCF₂— from the standpoint of excellentcompatibility with other liquid crystal compounds, and is preferably—CH═CH— or —C≡C— from the standpoint of a large optical anisotropy.

In the case where Z¹ and Z² are —CH═CH—, the steric configuration withrespect to the double bond for the other group is preferably a transconfiguration. Owing to the steric configuration, the liquid crystalcompound has a wide temperature range of a liquid crystal phase, and byadding the liquid crystal compound to a liquid crystal composition, thecomposition has a high maximum temperature (T_(NI)) of a nematic phase.

In the case where Z¹ and Z² include —CH═CH—, the compound has a widetemperature range of a liquid crystal phase, has a large elasticconstant ratio K₃₃/K₁₁ (K₃₃: bend elastic constant, K₁₁: splay elasticconstant), and has a small viscosity, and by adding the compound to aliquid crystal composition, the composition has a high maximumtemperature (T_(NI)) of a nematic phase.

The liquid crystal compound (a) may include an isotope, such as ²H(deuterium) and ¹³C, in an amount larger than the natural abundancesince there is no large difference in properties of the compounds.

The properties, such as the dielectric anisotropy, of the liquid crystalcompound (a) can be controlled to desired values by appropriatelyselecting Ra, Rb, ring A¹, ring A², Z¹ and Z² within the aforementionedranges.

Among the compounds represented by formula (a), in the case where ringA¹ and ring A² are each independently trans-1,4-cyclohexylene or1,4-phenylene, Z¹ and Z² are single bonds, l+m is 0 or 1, and n is aninteger of from 0 to 6, the compound is excellent in heat resistance andlight resistance. Among these, a compound, in which n is 0, 2, 4 or 6 ispreferred since it has a high maximum temperature of a nematic phase anda small viscosity, and a compound, in which n is 1, 3 or 5 is preferredsince it is excellent in compatibility with other liquid crystalcompounds.

Among the compounds, a compound, in which Ra is hydrogen, alkyl having 1to 10 carbons or alkenyl having 2 to 10 carbons, and Rb is alkyl having1 to 10 carbons or alkoxy having 1 to 9 carbons, is preferred since itexhibits excellent heat resistance and light resistance, and has a smallviscosity, a further low minimum temperature of a nematic phase and afurther high maximum temperature of a nematic phase. In particular, inthe case where l+m is 1, the maximum temperature of a nematic phase canbe moreover increased.

In the case where a liquid crystal compound has a structure representedby the liquid crystal compound (a), the compound has a suitable negativedielectric anisotropy, and has significantly good compatibility withother liquid crystal compounds. Furthermore, the compound has stabilityto heat, light and so forth, exhibits a nematic phase in a widetemperature range, and has a small viscosity, a large optical anisotropyand a suitable elastic constant K₃₃. A liquid crystal compositionincluding the liquid crystal compound (a) is stable under the conditionwhere a liquid crystal display device is generally used, and thecompound does not deposited as crystals (or a smectic phase) even uponstoring at a low temperature.

Accordingly, the liquid crystal compound (a) can be preferably used in aliquid crystal composition used in a liquid crystal display device ofsuch a display mode as PC, TN, STN, ECB, OCB, IPS and VA, and can beparticularly preferably used in a liquid crystal composition used in aliquid crystal display device of such a display mode as IPA and VA.

Synthesis of Liquid Crystal Compound (a)

The liquid crystal compound (a) can be synthesized by appropriatelycombining synthesis methods of synthetic organic chemistry. Examples ofa method for introducing the target end groups, rings and bonding groupsinto starting materials are disclosed in such literatures as ORGANICSYNTHESES (John Wiley & Sons, Inc.), ORGANIC REACTIONS (John Wiley &Sons, Inc.), COMPREHENSIVE ORGANIC SYNTHESIS (Pergamon Press), NEWEXPERIMENTAL CHEMISTRY COURSE (Shin Jikken Kagaku Kouza) (Maruzen,Inc.), and so forth.

Formation of Cyclohexenylene

One example of a method for forming cyclohexenylene is described withthe scheme shown below. In the scheme, MSG¹ and MSG² are each amonovalent organic group. Plural groups of MSG¹ (or MSG²) used in thescheme may be the same as or different from each other. The compound(1A) corresponds to the liquid crystal compounds (a).

An organic halogen compound (a1) having a monovalent organic group MSG²and magnesium are reacted with each other to prepare a Grignard reagent.In alternative, a compound (a3) having a monovalent organic group MSG²and n-butyllithium or sec-butyllithium are reacted with each other toprepare a lithium salt. The Grignard reagent or lithium salt thusprepared and a cyclohexanone derivative (a2) are reacted with each otherto prepare a corresponding alcohol derivative. Subsequently, theresulting alcohol derivative is subjected to dehydration by using anacid catalyst, such as p-toluenesulfonic acid, to synthesize a compound(1A) having a cyclohexenylene corresponding to the liquid crystalcompound (a). The cyclohexanone derivative (a2) can be synthesizedaccording, for example, to a method disclosed in JP S59-7122 A/1984.

Formation of Bonding Groups Z¹ and Z²

One example of a method for forming the bonding groups Z¹ and Z² isdescribed. A scheme of forming the bonding group is shown below. In thescheme, MSG¹ and MSG² are each a monovalent organic group. Plural groupsof MSG¹ (or MSG²) used in the scheme may be the same as or differentfrom each other. The compounds (1B) to (1I) correspond to the liquidcrystal compounds (a).

Formation of Double Bond

An organic halogen compound (a1) having a monovalent organic group MSG²and magnesium are reacted with each other to prepare a Grignard reagent.The Grignard reagent thus prepared and an aldehyde derivative (a4) or(a5) are reacted with each other to synthesize a corresponding alcoholderivative. Subsequently, the resulting alcohol derivative is subjectedto dehydration by using an acid catalyst, such as p-toluenesulfonicacid, to synthesize a corresponding compound (1B) or (a6) having adouble bond.

A compound obtained by treating an organic halogen compound (a1) withbutyllithium or magnesium is reacted with a formamide compound, such asN,N-dimethylformamide (DMF), to obtain an aldehyde derivative (a7). Theresulting aldehyde derivative (a7) is reacted with phosphonium ylideobtained by treating a phosphonium salt (a8) with a base, such aspotassium t-butoxide (t-BuOK), to synthesize a corresponding compound(1B) having a double bond. In the aforementioned reaction, there arecases where a cis compound is formed depending on the reactionconditions, and therefore, in the case where a trans compound isnecessarily obtained, the cis compound is isomerized to the transcompound by a known method.

Formation of —(CH₂)₂—

A compound (1B) is hydrogenated in the presence of a catalyst, such ascarbon supported palladium (Pd/C), to synthesize a compound (1C).

Formation of —(CH₂)₄—

An aldehyde derivative (a7) is reacted with phosphonium ylide obtainedby treating a phosphonium salt (a9) with a base, such as potassiumt-butoxide (t-BuOK), to synthesize a corresponding compound (a6) havinga double bond. A compound (a6) is hydrogenated in the presence of acatalyst, such as Pd/C, to synthesize a compound (1D).

Formation of Single Bond 1

An organic halogen compound (a10) having a monovalent organic group MSG¹and magnesium or butyllithium are reacted with each other to prepare aGrignard reagent or a lithium salt. The Grignard reagent or lithium saltthus prepared and a borate ester, such as trimethyl borate, are reactedwith each other and subjected to hydrolysis with an acid, such ashydrochloric acid, to prepare a dihydroxyborane derivative (a11). Thehydroxyborane derivative (a11) and an organic halogen compound (a1) arereacted with each other in the presence of a catalyst, such as acatalyst including a carbonate salt aqueous solution andtetrakis(triphenylphosphine) palladium (Pd(PPh₃)₄), to synthesize acompound (1E).

In alternative, an organic halogen compound (a10) is reacted withbutyllithium and then reacted with zinc chloride to obtain a compound,and the resulting compound is reacted with a compound (a1) in thepresence of a catalyst, such as bistriphenylphosphine dichloropalladium(Pd(PPh₃)₂Cl₂), to synthesize a compound (1E).

Formation of —CH₂O— or —OCH₂—

A dihydroxyborane derivative (a11) is oxidized with an oxidizing agent,such as hydrogen peroxide, to obtain an alcohol derivative (a12).Separately, an aldehyde derivative (a7) is reduced with a reducingagent, such as sodium borohydride, to obtain an alcohol derivative(a13). The resulting alcohol derivative (a13) is halogenated withhydrobromic acid or the like to obtain an organic halogen compound(a14). The alcohol derivative (a12) and the organic halogen compound(a14) thus obtained are reacted with each other in the presence ofpotassium carbonate or the like to synthesize a compound (1F).

Formation of —COO— and —OCO—

A compound (a10) is reacted with n-butyllithium and then reacted withcarbon dioxide to obtain a carboxylic acid derivative (a15). Thecarboxylic acid derivative (a15) and a phenol derivative (a16) aresubjected to dehydration in the presence of DCC (1,3-dicyclohexylcarbodiimide) and DMAP (4-dimethylaminopyridine) to synthesize acompound (1G) having —COO—. A compound having —OCO— can also besynthesized in the same manner.

Formation of —CF₂O— and —OCF₂—

A compound (1G) is treated with sulfurizing agent, such as Lawesson'sreagent, to obtain a compound (a17). The compound (a17) is fluorinatedwith a hydrogen fluoride pyridine complex and NBS (N-bromosuccinimide)to synthesize a compound having —CF₂O— (1H). The reaction is describedin M. Kuroboshi, et al., Chem. Lett., 827 (1992). The compound (1H) canalso be synthesized by fluorinating the compound (a17) with(diethylamino)sulfate trifluoride (DAST). The reaction is described inW. H. Bunnelle, et al., J. Org. Chem., 55, 768 (1990). A compound having—OCF₂— can also be synthesized in the same manner. These bonding groupscan also be formed by a method disclosed in Peer. Kirsch, et al., Anbew.Chem. Int. Ed., 40, 1480 (2001).

Formation of —C≡C—

A compound (a10) is reacted with 2-methyl-3-butyne-2-ol in the presenceof dichloropalladium and copper halide as a catalyst, and thendeprotected under a basic condition to obtain a compound (a18). Thecompound (a18) is reacted with a compound (a1) in the presence ofdichloropalladium and copper halide as a catalyst to synthesize acompound (1I).

Production Method of Liquid Crystal Compound (a)

An example of a production method of the liquid crystal compound (a),i.e., the liquid crystal compound represented by formula (a), is shownbelow.

A compound (b1) and sec-BuLi are reacted with each other to prepare alithium salt. The lithium salt and a carbonyl derivative (b2) arereacted with each other to obtain an alcohol derivative (b3). Theresulting alcohol derivative (b3) is subjected to dehydration in thepresence of an acid catalyst, such as p-toluenesulfonic acid, to obtaina cyclohexene derivative (b4). The compound (b4) is hydrolyzed in anacidic atmosphere, such as formic acid, to obtain a carbonyl derivative(b5). The resulting carbonyl derivative (b5) is subjected to Wittigreaction with phosphonium ylide, which is prepared frommethoxymethyltriphenylphosphonium chloride and a base, such as potassiumt-butoxide (t-BuOK), to obtain an enol ether derivative (b6). Theresulting enol ether derivative (b6) is hydrolyzed in an acidicatmosphere, and depending on necessity, is then isomerized in a basicatmosphere, to obtain an aldehyde derivative (b7). The aldehydederivative (b7) is reacted with phosphonium ylide, which is preparedfrom butyltriphenylphosphonium bromide and a base, such as t-BuOK, toobtain a mixture (b8) of an E-alkene and a Z-alkene. The mixture is thenisomerized in the presence of sodium benzenesulfinate and hydrochloricacid to produce a liquid crystal compound (b9), which is an example ofthe liquid crystal compound (a) of the invention.

Liquid Crystal Composition

The liquid crystal composition of the invention is described below. Theliquid crystal composition includes at least one liquid crystal compound(a), and the liquid crystal composition may include two or more liquidcrystal compounds (a) and may be constituted only by the liquid crystalcompound (a). Upon preparing the liquid crystal composition of theinvention, the components may be selected in consideration, for example,of the dielectric anisotropy of the liquid crystal compound (a).

The liquid crystal composition has a low viscosity, has a suitablenegative dielectric anisotropy, has a suitable elastic constant K₃₃, hasa low threshold voltage, has a high maximum temperature of a nematicphase (high phase transition temperature from a nematic phase to anisotropic phase), and has a low minimum temperature of a nematic phase.

Liquid Crystal Composition (1)

The liquid crystal composition of the invention is preferably acomposition that includes, in addition to the liquid crystal compound(a) as a first component, at least one compound selected from a group ofliquid crystal compounds represented by formulae (e-1) to (e-3) (whichmay be referred to as the compounds (e-1) to (e-3)) as a secondcomponent. The composition may be referred to as a liquid crystalcomposition (1).

In formulae (e-1) to (e-3), Ra₁₁ and Rb₁₁ are each independently alkylhaving 1 to 10 carbons, provided that in the alkyl, —CH₂— that are notadjacent to each other may be replaced by —O—, —(CH₂)₂— that are notadjacent to each other may be replaced by —CH═CH—, and hydrogen may bereplaced by fluorine.

In formulae (e-1) to (e-3), ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴are each independently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.

In formulae (e-1) to (e-3), Z¹¹, Z¹² and Z¹³ are each independently asingle bond, —CH₂—CH₂—, —CH═CH—, —C≡C—, —COO— or —CH₂O—.

By adding the second component to the liquid crystal compound (a), theliquid crystal composition has a small viscosity and a wide range of anematic phase.

For example, the compound (e-1) is a compound that is effective fordecreasing the viscosity of a liquid crystal composition including thecompound and for increasing the specific resistance of the composition.

The compound (e-2) is a compound that is effective for increasing themaximum temperature of a nematic phase of a liquid crystal compositionincluding the compound and for increasing the specific resistance of thecomposition.

The compound (e-3) is a compound that is effective for increasing themaximum temperature of a nematic phase of a liquid crystal compositionincluding the compound and for increasing the specific resistance of thecomposition.

In ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴, in the case where two ormore rings are trans-1,4-cyclohexylene, the maximum temperature of anematic phase of a liquid crystal compound including the compound can beincreased, and in the case where two or more rings are 1,4-phenylene,the optical anisotropy of a liquid crystal compound including thecompound can be increased.

Preferred examples of the second component include compounds representedby formulae (2-1) to (2-74) below (which may be referred to as compounds(2-1) to (2-74)). In these compounds, Ra₁₁ and Rb₁₁ have the samemeanings as in the compounds (e-1) to (e-3).

In the case where the second component is the compounds (2-1) to (2-74),such a liquid crystal composition can be prepared that exhibitsexcellent heat resistance and light resistance, has a further highspecific resistance and a wide range of a nematic phase.

In the liquid crystal composition (1) of the invention, the content ofthe second component is not particularly limited and is preferably largefrom the standpoint of decreasing the viscosity. However, there is atendency that the threshold voltage of the liquid crystal composition isincreased by increasing the content of the second component, andtherefore, in the case where the liquid crystal composition of theinvention is used in a liquid crystal device of a VA mode, for example,it is more preferred that the content of the second component is in arange of from approximately 15% to approximately 70% by weight based onthe total weight of the liquid crystal composition, and the firstcomponent is in a range of from approximately 30% to approximately 85%by weight based on the total weight of the liquid crystal composition.

In particular, in the case where the liquid crystal composition (1)includes at least one compound selected from a group of compounds,wherein in formula (a), Ra is hydrogen or alkyl having 1 to 10 carbons,and Rb is alkoxy having 1 to 9 carbons, as the first component, and atleast one compound selected from a group of compounds (e-1) to (e-3) asthe second component, the liquid crystal composition (1) exhibitsexcellent heat resistance and light resistance, has a wide range of anematic phase, has a large specific resistance, has a small viscosityand has a suitable elastic constant K₃₃.

Liquid Crystal Composition (2)

The liquid crystal composition of the invention is preferably acomposition that includes, in addition to the first component and thesecond component, at least one compound selected from a group of liquidcrystal compounds represented by formulae (g-1) to (g-4) (which may bereferred to as the compounds (g-1) to (g-4)) as a third component. Thecomposition may be referred to as a liquid crystal composition (2).

In formulae (g-1) to (g-4), Ra₂₁ and Rb₂₁ are each independentlyhydrogen or alkyl having 1 to 10 carbons, provided that in the alkyl,—CH₂— that are not adjacent to each other may be replaced by —O—,—(CH₂)₂— that are not adjacent to each other may be replaced by —CH═CH—,and hydrogen may be replaced by fluorine.

In formulae (g-1) to (g-4), ring A²¹, ring A²² and ring A²³ are eachindependently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl ortetrahydropyran-2,5-diyl.

In formulae (g-1) to (g-4), Z²¹, Z²² and Z²³ are each independently asingle bond, —CH₂—CH₂—, —CH═CH—, —C≡—, —OCF₂—, —CF₂O—, —OCF₂CH₂CH₂—,—CH₂CH₂CF₂O—, —COO—, —OCO—, —OCH₂— or —CH₂O—, and Y¹, Y², Y³ and Y⁴ areeach independently fluorine or chlorine.

In formulae (g-1) to (g-4), q, r and s are each independently 0, 1 or 2,provided that q+r+s is 1, 2 or 3, and t is 0, 1 or 2.

The liquid crystal composition (2) further including the third componenthas a negatively large dielectric anisotropy. The composition also has awide temperature range of a nematic phase, has a small viscosity, has anegatively large dielectric anisotropy, provides a liquid crystalcomposition having a large specific resistance, and provides a liquidcrystal composition being properly balanced among the properties.

The third component is preferably at least one compound selected from agroup of compounds represented by formulae (h-1) to (h-5) (which may bereferred to as compounds (h-1) to (h-5)) from the standpoint ofdecreasing a viscosity and improving resistance to heat and light.

In formulae (h-1) to (h-5), Ra₂₂ is linear alkyl having 1 to 8 carbonsor linear alkenyl having 2 to 8 carbons, Rb₂₂ is linear alkyl having 1to 8 carbons, linear alkenyl having 2 to 8 carbons or alkoxy having 1 to7 carbons, and Z²⁴ is a single bond or —CH₂CH₂—.

In formulae (h-1) to (h-5), both Y¹ and Y² are fluorine, or one of Y¹and Y² is fluorine, and the other is chlorine.

For example, a compound having a condensed ring, such as the compounds(g-2) to (g-4), can decrease the threshold voltage of a liquid crystalcomposition including the compound. For example, the compounds (h-1) and(h-2) can decrease the viscosity of a liquid crystal compositionincluding the compound and can further decrease the threshold voltage ofthe composition. The compounds (h-2) and (h-3) can increase the maximumtemperature of a nematic phase of a liquid crystal composition includingthe compound, can further decrease the threshold voltage of thecomposition, and can increase the optical anisotropy of the composition.The compounds (h-4) and (h-5) can increase the maximum temperature of anematic phase of a liquid crystal composition including the compound,can increase the optical anisotropy of the composition, and can decreasethe threshold voltage of the composition.

In particular, in the case where the liquid crystal composition (2)includes at least one compound selected from a group of compounds,wherein in formula (a), Ra is hydrogen or alkyl having 1 to 10 carbons,and Rb is alkoxy having 1 to 9 carbons, as the first component, at leastone compound selected from a group of compounds (e-1) to (e-3) as thesecond component, and at least one compound selected from a group ofcompounds represented by formulae (h-1), (h-2), (h-3), (h-4) and (h-5)as the third component, the liquid crystal composition (2) exhibitsexcellent heat resistance and light resistance, has a wide range of anematic phase, has a small viscosity, has a negatively large dielectricanisotropy, has a large specific resistance and has a suitable elasticconstant K₃₃. The liquid crystal composition is preferred since it isproperly balanced among the properties.

Preferred examples of the third component include compounds (3-1) to(3-68) below. In these compounds, Ra₂₂ and Rb₂₂ have the same meaningsas in the compounds (h-1) to (h-5).

In the liquid crystal composition (2) of the invention, the content ofthe third component is not particularly limited and is preferably largefrom the standpoint of preventing the absolute value of the negativedielectric anisotropy from being decreased.

While the contents of the first component, the second component and thethird component in the liquid crystal composition (2) are notparticularly limited, it is preferred that the content of the liquidcrystal compound (a) is in a range of from approximately 10% toapproximately 80% by weight, the content of the second component is in arange of from approximately 10% to approximately 80% by weight, and thecontent of the third component is in a range of from approximately 10%to approximately 80% by weight, based on the total weight of the liquidcrystal composition (2), and it is more preferred that the content ofthe liquid crystal compound (a) is in a range of from approximately 10%to approximately 70% by weight, the content of the second component isin a range of from approximately 10% to approximately 50% by weight, andthe content of the third component is in a range of from approximately20% to approximately 60% by weight, based on the total weight of theliquid crystal composition (2).

In the case where the content of the first component, the secondcomponent and the third component in the liquid crystal composition (2)are in the aforementioned ranges, a liquid crystal composition can beobtained that exhibits excellent heat resistance and light resistance,has a wide temperature range of a nematic phase, has a small viscosity,has a large negative dielectric anisotropy, has a large specificresistance and has a suitable elastic constant K₃₃, and furthermore, aliquid crystal composition that is properly balanced among theproperties can be obtained.

Embodiments of Liquid Crystal Composition

The liquid crystal composition of the invention may include, in additionto the first component and the second and third components optionallyadded, another liquid crystal compound for purpose, for example, offurther controlling the properties of the liquid crystal composition.The liquid crystal composition of the invention may be used withoutaddition of any other liquid crystal compound than the liquid crystalcompounds constituting the first component and the second and thirdcomponents optionally added, from the standpoint, for example, of cost.

The liquid crystal composition of the invention may further include anadditive, such as an optically active compound, a coloring matter, adefoaming agent, an ultraviolet light absorbent, an antioxidant and soforth.

In the case where an optically active compound is added to the liquidcrystal composition of the invention, a helical structure is induced inliquid crystal to provide a twist angle. In the case where a coloringmatter is added to the liquid crystal composition of the invention, theliquid crystal composition can be applied to a liquid crystal displaydevice having a GH (guest host) mode. In the case where a defoamingagent is added to the liquid crystal composition of the invention, theliquid crystal composition can be prevented from being foamed duringtransportation of the liquid crystal composition and during process ofproducing a liquid crystal display device from the liquid crystalcomposition. In the case where an ultraviolet light absorbent or anantioxidant is added to the liquid crystal composition of the invention,the liquid crystal composition and a liquid crystal display deviceincluding the liquid crystal composition can be prevented from beingdeteriorated. For example, an antioxidant can suppress the specificresistance from being decreased upon heating the liquid crystalcomposition.

Examples of the ultraviolet light absorbent include a benzophenoneultraviolet light absorbent, a benzoate ultraviolet light absorbent anda triazole ultraviolet light absorbent. Specific examples of thebenzophenone ultraviolet light absorbent include2-hydroxy-4-n-octoxybenzophenone. Specific examples of the benzoateultraviolet light absorbent include 2,4-di-t-butylphenyl3,5-di-t-butyl-4-hydroxybenzoate. Specific examples of the triazoleultraviolet light absorbent include2-(2-hydroxy-5-methylphehyl)benzotriazole,2-(2-hydroxy-3-(3,4,5,6-tetrahydroxyphthalimide-methyl)-5-methylphenyl)benzotriazoleand 2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole.

Examples of the antioxidant include a phenol antioxidant and an organicsulfur antioxidant. An antioxidant represented by formula (I) below ispreferred since it has a high antioxidant activity without changing theproperties of the liquid crystal composition.

In formula (I), w is an integer of 1 to 15.

Specific examples of the phenol antioxidant include2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol,2,6-di-t-butyl-4-propylphenol, 2,6-di-t-butyl-4-butylphenol,2,6-di-t-butyl-4-pentylphenol, 2,6-di-t-butyl-4-hexylphenol,2,6-di-t-butyl-4-heptylphenol, 2,6-di-t-butyl-4-octylphenol,2,6-di-t-butyl-4-nonylphenol, 2,6-di-t-butyl-4-decylphenol,2,6-di-t-butyl-4-undecylphenol, 2,6-di-t-butyl-4-dodecylphenol,2,6-di-t-butyl-4-tridecylphenol, 2,6-di-t-butyl-4-tetradecylphenol,2,6-di-t-butyl-4-pentadecylphenol,2,2′-methylenebis(6-t-butyl-4-methylphenol),4,4′-butylidenebis(6-t-butyl-3-methylphenol),2,6-di-t-butyl-4-(2-octadecyloxycarbonyl)ethylphenol and pentaerythritoltetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate).

Specific examples of the organic sulfur antioxidant include dilauryl3,3′-thiopropionate, dimyristyl 3,3′-thiopropionate, distearyl3,3′-thiopropionate, pentaerythritol tetrakis(3-laurylthiopropionate)and 2-mercaptobenzimidazole.

The addition amount of the additive, which is represented by anultraviolet light absorbent and an antioxidant, may be such an amountthat does not impair the advantages of the invention and attains theadvantages of addition of the additive.

For example, in the case where the ultraviolet light absorbent or theantioxidant is added, the addition ratio thereof is generally fromapproximately 10 ppm to approximately 500 ppm, preferably fromapproximately 30 ppm to approximately 300 ppm, and more preferably fromapproximately 40 ppm to approximately 200 ppm, based on the total weightof the liquid crystal composition of the invention.

The liquid crystal composition of the invention may include impurities,such as a synthesis raw material, a by-product, a reaction solvent and asynthesis catalyst, which are mixed during the synthesis process of thecompounds of the liquid crystal composition and during the preparationprocess of the liquid crystal composition.

Production Method of Liquid Crystal Composition

The liquid crystal composition of the invention can be produced in thefollowing manner. In the case where compounds as the constitutionalcomponents are in a liquid state, the compounds may be mixed and shakento prepare the composition. In the case where compounds as theconstitutional components include a solid, the compounds may be mixedand heated to make the solid into a liquid state, followed by shaking,to prepare the composition. The liquid crystal composition of theinvention may be produced in any other known methods.

Properties of Liquid Crystal Composition

The liquid crystal composition of the invention can have a maximumtemperature of a nematic phase of approximately 70° or more, and aminimum temperature of a nematic phase of approximately −20° or less,and thus has a wide temperature range of a nematic phase. Accordingly, aliquid crystal display device including the liquid crystal compositioncan be used in a wide temperature range.

In the liquid crystal composition of the invention, the opticalanisotropy can be controlled to a range of approximately 0.10 toapproximately 0.13, and further to a range of from approximately 0.05 toapproximately 0.18, by appropriately adjusting the formulation and soforth. In the liquid crystal composition of the invention, a liquidcrystal composition that generally has a dielectric anisotropy of fromapproximately −5.0 to approximately −2.0, and preferably fromapproximately −4.5 to approximately −2.5, can be obtained. A liquidcrystal composition within the aforementioned ranges can be preferablyused in a liquid crystal display device operated in an IPS mode and a VAmode.

Liquid Crystal Display Device

The liquid crystal composition of the invention can be used not only ina liquid display device operated in an AM mode having an operation mode,such as a PC mode, a TN mode, an STN mode and an OCB mode, but also in aliquid display device operated in a passive matrix (PM) mode having anoperation mode, such as a PC mode, a TN mode, an STN mode, an OCB mode,a VA mode and an IPS mode. The liquid crystal display device of an AMmode and a PM mode can be applied to any liquid crystal display of areflection type, a transmission type and a semi-transmission type.

The liquid crystal display device of the invention can be used as a DS(dynamic scattering) mode device using a liquid crystal compositionincluding a conductive agent, an NCAP (nematic curvilinear alignedphase) device prepared by microcapsulating the liquid crystalcomposition, and as a PD (polymer dispersed) device having athree-dimensional network polymer formed in the liquid crystalcomposition, for example, a PN (polymer network) device.

Among these, the liquid crystal composition of the invention can bepreferably used in a liquid crystal display device of an AM mode drivenin an operation mode utilizing a liquid crystal composition having anegative dielectric anisotropy, such as a VA mode and an IPS mode, andparticularly preferably used in a liquid crystal display device of an AMmode driven in a VA mode, owing to the properties of the compositionmentioned above.

In a liquid crystal display device driven in a TN mode, a VA mode and soforth, the direction of the electric field is perpendicular to theliquid crystal layer. In a liquid crystal display device driven in anIPS mode and so forth, the direction of the electric field is inparallel to the liquid crystal layer. A structure of a liquid crystaldisplay device driven in a VA mode is reported in K. Ohmuro, S. Kataoka,T. Sasaki and Y. Koike, SID '97 Digest of Technical Papers, 28, 854(1997), and a structure of a liquid crystal display device driven in anIPS mode is reported in WO 91/10936 (corresponding to U.S. Pat. No.5,576,867).

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES Example of Liquid Crystal Compound (a)

The invention will be described in more detail with reference to examplebelow, but the invention is not construed as being limited to theseexamples. All occurrences of “%” are by weight unless otherwiseindicate.

The resulting compounds are identified by magnetic nuclear resonancespectra obtained by ¹H-NMR analysis, gas chromatograms obtained by gaschromatography (GC) analysis, and so forth, as described below.

¹H-NMR Analysis: A DRX-500 (produced by Bruker Biospin Co., Ltd.) wasused for measurement. A sample produced in the examples and so forth wasdissolved in a deuterated solvent capable of dissolving the sample, suchas CDCl₃, and the measurement was carried out at room temperature and500 MHz with an accumulated number of 24. In the description of theresulting nuclear resonance spectra, “s” means a singlet, “d” means adoublet, “t” means a triplet, “q” means a quartet, and “m” means amultiplet. Tetramethylsilane (TMS) was used as a standard substanceindicating zero point of chemical shift δ.

GC Analysis: A Chromatograph Model GC-14B made by Shimadzu was used formeasurement. Capillary column CBP1-M25-025 (length: 25 m, bore: 0.32 mm,film thickness: 0.25 μm, dimethylpolysiloxane as stationary phase, nopolarity) produced by Shimadzu Corp. was used as a column. Helium wasused as a carrier gas, and adjusted to a flow rate of 1 mL/minute. Thetemperature of a sample vaporizing chamber was 280° C., and thetemperature of the detector (FID) was 300° C.

The sample was dissolved in toluene to prepare a 1% by weight solution,and 1 μL of the resulting solution was injected into the samplevaporizing chamber.

A Chromatopac Model C-R6A, produced by Shimadzu Corp., or an equivalentthereof, was used as a recorder. The gas chromatogram obtained showed aretention time of a peak and a peak area corresponding to the componentcompound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used: a capillarycolumn DB-1, produced by Agilent Technologies Inc. (length: 30 m, bore:0.32 mm, film thickness: 0.25 μm), a capillary column HP-1, produced byAgilent Technologies Inc. (length: 30 m, bore: 0.32 mm, film thickness:0.25 μm), a capillary column Rtx-1, produced by Restek Corporation(length: 30 m, bore: 0.32 mm, film thickness: 0.25 μm), and a capillarycolumn BP-1, produced by SGE International Pty. Ltd. (length: 30 m,bore: 0.32 mm, film thickness: 0.25 μm).

An area ratio of each peak in the gas chromatogram corresponds to aratio of the component compound. In general, the percentages by weightof the component compounds of the analyzed sample are not completelyidentical to the percentages by area of the peaks of the analyzedsample. According to the invention, however, the percentages by weightof the component compounds of the analyzed sample substantiallycorrespond to the percentages by area of the peaks of the analyzedsample because the correction coefficient is substantially 1 when theaforementioned columns are used in the invention because there is nosignificant difference in correction efficient of component compounds.In order to obtain accurately compositional ratios of liquid crystalcompounds in a liquid crystal composition, an internal reference methodin gas chromatogram is used. The liquid crystal compound (sample to bemeasured) and a liquid crystal compound as a reference (referencesubstance), which have been weighed accurately to prescribed amounts,are simultaneously measured by gas chromatography, and a relativeintensity of an area ratio of a peak of the sample to be measured and apeak of the reference substance is calculated in advance. Thecompositional ratios of the liquid crystal compounds in the liquidcrystal composition can be accurately obtained by correcting by usingthe relative intensity of the peak areas of the component compounds withrespect to the reference substance.

Sample of Liquid Crystal Compound for Measuring Characteristics

A sample of the liquid crystal compound for measuring characteristicsincludes two cases, i.e., the case where the compound itself is used asa sample, and the case where the compound is mixed with base mixtures toprepare a sample.

In the later case where a sample is prepared by mixing the compound withbase mixtures, the measurement is carried out in the following manner. Asample was produced by mixing 15% by weight of the compound and 85% byweight of base mixtures. A value of characteristics of the compound wascalculated by extrapolating from a value obtained by measurement:Extrapolated Value=(100×(measured value of sample)−(percentage by weightof base mixtures)×(value measured for base mixtures))/(percentage byweight of liquid crystal compound.

In the case where a smectic phase or crystals were deposited at 25° C.at this ratio of the liquid crystal compound and the base mixtures, theratio of the compound and the base mixtures was changed step by step inthe order of (10% by weight/90% by weight), (5% by weight/95% byweight), (1% by weight/99% by weight), respectively. The value ofcharacteristics of the sample was measured at a ratio where a smecticphase or crystals were not deposited at 25° C., and an extrapolatedvalue was obtained by the aforementioned equation, which was designatedas a value of characteristics of the liquid crystal compound.

While there are various kinds of base mixtures for the aforementionedmeasurement, the compositions of the base mixtures (i) were, forexample, as follows:

Base Mixtures (i)

As a sample for measuring a value of characteristics of a liquid crystalcomposition, the liquid crystal composition itself was used.

Measurement Method of Characteristics of Liquid Crystal Compound

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectric Industries Association of Japan, EIAJ ED-2521 A or those withsome modifications. A TFT was not attached to a TN device or a VA deviceused for measurement.

Among the measured values, the values obtained with the liquid crystalcompound itself as a sample and the values obtained with the liquidcrystal composition itself as a sample were described as experimentaldata. In the case where the values were obtained with the mixture of thecompound with the base mixtures, the extrapolated values were describedas experimental data.

Phase Structure and Phase Transition Temperature (° C.)

The measurement was carried out in the methods (1) and (2) below.

A compound was placed on a hot plate (Hot Stage Model FP-52, produced byMettler Co., Ltd.) in a melting point apparatus equipped with apolarizing microscope, and while heating at the rate of 3° C. perminute, the state of the phase and the changes thereof were observedwith the polarizing microscope to determine the kind of the phase.

A sample was heated and cooled at a rate of 3° C. per minute by using ascanning calorimeter, DSC-7 System or Diamond DSC System, produced byPerkin-Elmer, Inc., whereby a starting point of an endothermic peak oran exothermic peak associated with phase change of the sample wasobtained by extrapolation (on set) to determine phase transitiontemperature.

In the following description, a crystal is denoted by “C.” In the casewhere a crystal is distinguished into two crystals, they are denoted by“C₁” and “C₂,” respectively. A smectic phase is denoted by “S,” and anematic phase is denoted by “N.” A liquid (isotropic phase) is denotedby “I.” In the case where a smectic phase is distinguished into asmectic B phase and a smectic A phase, they are denoted by “S_(B)” and“S_(A),” respectively. The expression of the phase transitiontemperature, “C 50.0 N 100.0 I,” for example, means that the transitiontemperature of from a crystal to a nematic phase (CN) is 50.0° C., andthe transition temperature of from a nematic phase to a liquid (NI) is100.0° C. The other expressions are applied with the same rule.

Maximum Temperature of Nematic Phase (T_(NI); ° C.): A sample (a liquidcrystal composition or a mixture of a liquid crystal compound and thebase mixtures) was placed on a hot plate (Hot Stage Model FP-52,produced by Mettler Co., Ltd.) in a melting point apparatus equippedwith a polarizing microscope, and while heating at the rate of 1° C. perminute, was observed with the polarizing microscope. A temperature wherea part of the sample was changed from a nematic phase to an isotropicliquid was designated as a maximum temperature of a nematic phase. Themaximum temperature of a nematic phase may be abbreviated to “a maximumtemperature” in some cases.

Low Temperature Compatibility: Samples were prepared by mixing the basemixtures and a liquid crystal compound to make a ratio of the liquidcrystal compound of 20% by weight, 15% by weight, 10% by weight, 5% byweight, 3% by weight and 1% by weight, respectively, and then placed inglass bottles. The glass bottles were stored in a freezer at −10° C. or−20° C. for a prescribed period of time, and then were observed as towhether or not a crystal or a smectic phase was deposited.

Viscosity (η; measured at 20° C.; mPa·s): The viscosity was measured bymeans of an E-type viscometer.

Rotation Viscosity (γ1; measured at 25° C.; mPa·s): The rotationviscosity was measured according to the method disclosed in M. Imai, etal., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). Asample (a liquid crystal composition or a mixture of a liquid crystalcompound and the base mixtures) was placed in a VA device having a cellgap between two glass plates of 20 μm. The VA device was impressed witha voltage in a range of from 30 V to 50 V stepwise by 1 V. After aperiod of 0.2 second with no impress of voltage, voltage impress wasrepeated with only one rectangular wave (rectangular pulse of 0.2second) and application of no voltage (2 seconds). A peak current and apeak time of a transient current generated by the voltage impress weremeasured. The rotation viscosity was obtained from the measured valuesand the calculating equation (8) in the literature by M. Imai, et al.,p. 40. As the dielectric anisotropy necessary for the calculation, thevalue measured by the measuring method of dielectric anisotropydescribed below.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using light having a wavelength of 589 nmat a temperature of 25° C. The surface of a main prism was rubbed in onedirection, and then a sample (a liquid crystal composition or a mixtureof a liquid crystal compound and the base mixtures) was dropped on themain prism. A refractive index (n∥) was measured when the direction ofpolarized light was parallel to that of the rubbing. A refractive index(n⊥) was measured when the direction of polarized light wasperpendicular to that of the rubbing. A value of optical anisotropy (Δn)was calculated from the equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.): The dielectricanisotropy was measured in the following manner. A solution ofoctadecyltriethoxysilane (0.16 mL) and ethanol (20 mL) was coated on aglass substrate having been well cleaned. The glass substrate was spunwith a spinner and then heated to 150° C. for 1 hour. A VA device havinga distance (cell gap) of 20 μm was fabricated with two sheets of theglass substrates. A polyimide oriented film was prepared on a glasssubstrate in the similar manner. The oriented film of the glasssubstrate was rubbed, and a TN device having a distance between twoglass substrates of 9 μm and a twist angle of 80° was fabricated. Asample (a liquid crystal composition or a mixture of a liquid crystalcompound and the base mixtures) was put in the VA device, which was thenimpressed with a voltage of 0.5 V (1 kHz, sine wave) to measure adielectric constant (∈∥) in the major axis direction of the liquidcrystal molecule. A sample (a liquid crystal composition or a mixture ofa liquid crystal compound and the base mixtures) was put in the TNdevice, which was then impressed with a voltage of 0.5 V (1 kHz, sinewave) to measure a dielectric constant (∈⊥) in the minor axis directionof the liquid crystal molecule. The dielectric anisotropy was calculatedfrom the equation: Δ∈=∈∥−∈⊥.

Voltage Holding Ratio (VHR; measured at 25° C.; %): A TN device used formeasurement has a polyimide-alignment film, and the cell gap between twoglass plates is 6 μm. A sample (a liquid crystal composition or amixture of a liquid crystal compound and base mixtures) was poured intothe device, and then the device was sealed with an adhesive which ispolymerized by the irradiation of an ultraviolet light. The TN devicewas impressed and charged with pulse voltage (60 microseconds at 5 V).The decreasing voltage was measured for 16.7 milliseconds with HighSpeed Voltmeter and the area A between a voltage curve and a horizontalaxis in a unit cycle was obtained. The area B was an area withoutdecreasing. Voltage holding ratio is a percentage of the area A to thearea B.

Elastic Constant (K₁₁, K₃₃; measured at 25° C.): Elastic constantmeasuring apparatus, Model EC-1, produced by TOYO Corp. was used formeasurement. A sample was poured into a vertical orientation cell havinga distance between two glass substrates (cell gap) of 20 μm. The cellwas impressed with a voltage of from 20 to 0 V to measure a capacitanceand an impressed voltage. The resulting values of capacitance (C) andimpressed voltage (V) were subjected to fitting by using the equations(2.98) and (2.101) disclosed in LIQUID CRYSTAL DEVICE HANDBOOK (NikkanKogyo Shimbun, Ltd.), p. 75, and an elastic constant was obtained by theequation (2.100).

Example 1 Synthesis of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-vinylbicyclohexyl-3-ene (No.132)

First Step: 6.1 g of well dried magnesium and 20 mL of THF were placedin a reactor under nitrogen atmosphere, and heated to 40° C. 59.7 g of1-bromo-4-ethoxy-2,3-difluorobenzene (1) dissolved in 300 mL of THF wasslowly added dropwise thereto at a temperature range of from 40 to 60°C., followed by stirring for 60 minutes. Thereafter, 50.0 g of4-(1,4-dioxaspiro[4,5]dec-8-yl)cyclohexanone (2) dissolved in 150 mL ofTHF was slowly added dropwise thereto at a temperature range of from 50to 60° C., followed by stirring for 60 minutes. After cooling theresulting reaction mixture to 30° C., the reaction mixture was mixedwith 900 mL of a 3% ammonium chloride aqueous solution and 500 mL oftoluene cooled to 0° C. in a vessel and separated into an organic layerand an aqueous layer by standing still, so as to attain extraction. Theresulting organic layer was fractionated and washed with water, asaturated sodium bicarbonate aqueous solution, and water, followed bydrying over anhydrous magnesium sulfate. Thereafter, the solvent wasdistilled off under reduced pressure to obtain 100.1 g of4-(1,4-dioxaspiro[4,5]dec-8-yl)-1-(4-ethoxy-2,3-difluorophenyl)cyclohexanol(3). The resulting compound (3) was a yellow solid.

Second Step: 100.1 g of the compound (3), 1.0 g of p-toluenesulfonicacid, 1.0 g of ethylene glycol and 300 mL of toluene were mixed, and themixture was refluxed under heating for 2 hours while water was removedby distillation. After cooling the resulting reaction mixture to 30° C.,500 mL of water and 900 mL of toluene were added to and mixed with thereaction mixture, which was separated into an organic layer and anaqueous layer by standing still, so as to attain extraction to theorganic layer. The resulting organic layer was fractionated and washedwith a saturated sodium bicarbonate aqueous solution and water, followedby drying over anhydrous magnesium sulfate. The resulting solution waspurified by silica gel column chromatography using toluene as eluent,and then further purified by recrystallization from a mixed solvent oftoluene and heptane (toluene/heptane=1/1 by volume), followed by drying,to obtain 58.1 g of8-(4-(4-ethoxy-2,3-difluorophenyl)-cyclohex-3-enyl-1,4-dioxasporo[4.5]decane(4). The yield based on the compound (2) was 73.2%.

Third Step: 58.1 g of the compound (4), 35.4 g of formic acid and 200 mLof toluene were mixed, and the mixture was refluxed under heating for 2hours. After cooling the reaction mixture to 30° C., 500 mL of water and1,000 mL of toluene were added to and mixed with the resulting solution,which was separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, asaturated sodium bicarbonate aqueous solution, and water, followed bydrying over anhydrous magnesium sulfate. Thereafter, the solvent wasremoved by distillation under reduced pressure to obtain 54 g of a paleyellow solid. 54 g of the solid, 35.4 g of formic acid and 200 mL oftoluene were mixed, and the mixture was refluxed under heating for 1hour. After cooling the reaction mixture to 30° C., 500 mL of water and1,000 mL of toluene were added to and mixed with the resulting solution,which was separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, asaturated sodium bicarbonate aqueous solution, and water, followed bydrying over anhydrous magnesium sulfate. Thereafter, the solvent wasremoved by distillation under reduced pressure, and the residue waspurified by recrystallization from a mixed solvent of toluene andheptane (toluene/heptane=1/2 by volume), followed by drying, to obtain49.7 g of 4′-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3′-en-4-one (5).The yield based on the compound (4) was 96.7%.

Fourth Step: 57.7 g of well dried methoxymethyltriphenylphosphoniumchloride and 200 mL of THF were mixed under nitrogen atmosphere andcooled to −30° C. Thereafter, 18.1 g of potassium t-butoxide (t-BuOK)was added thereto by dividing into 4 portions at a temperature range offrom −30 to −20° C. After stirring at −20° C. for 30 minutes, 45.0 g ofthe compound (5) dissolved in 135 mL of THF was added dropwise theretoat a temperature range of from −30 to −20° C. After stirring at −10° C.for 30 minutes, the reaction mixture was added to and mixed with amixture of 400 mL of water and 400 mL of toluene, which was separatedinto an organic layer and an aqueous layer by standing still, so as toattain extraction to the organic layer. The resulting organic layer wasfractionated and washed with water, followed by drying over anhydrousmagnesium sulfate. Thereafter, the solvent was concentrated underreduced pressure, and the residue was purified by silica gel columnchromatography using a mixed solvent of heptane and toluene(heptane/toluene=7/3 by volume) as eluent. The resulting eluate wasconcentrated under reduced pressure to obtain 51.6 g of4-(4-ethoxy-2,3-difluorophenyl)-4′-methoxymethylene-bicyclohexyl-3-ene(6) in pale yellow color.

Fifth Step: 51.6 g of the compound (6), 37.7 g of formic acid and 200 mLof toluene were mixed, and the mixture was refluxed under heating for 2hours. After cooling the reaction mixture to 30° C., 500 mL of water and1,000 mL of toluene were added to and mixed with the resulting solution,which was separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, asaturated sodium bicarbonate aqueous solution, and water, followed bydrying over anhydrous magnesium sulfate. Thereafter, the solvent wasremoved by distillation under reduced pressure to obtain 51.2 g of apale yellow solid. The residue was dissolved in 50 mL of toluene andadded to a mixture of 0.5 g of 95% sodium hydroxide and 400 mL ofmethanol cooled to 7° C., followed by stirring at 10° C. for 2 hours.Thereafter, 20 mL of a 2N sodium hydroxide aqueous solution was added,followed by stirring at 5° C. for 2 hours. The resulting reactionsolution was added to and mixed with a mixture of 2,000 mL of water and2,000 mL of toluene, which was separated into an organic layer and anaqueous layer by standing still, so as to attain extraction to theorganic layer. The resulting organic layer was fractionated and washedwith water, followed by drying over anhydrous magnesium sulfate.Thereafter, the solvent was removed by distillation under reducedpressure, and the resulting residue was purified by recrystallizationfrom a mixed solvent of heptane and THF (heptane/THF=4/1 by volume),followed by drying, to obtain 43.5 g of4′-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3′-ene-trans-4-carboaldehyde(7) as a white solid. The yield based on the compound (5) was 92.7%.

Sixth Step: 8.6 g of well dried methyltriphenylphosphonium bromide and40 mL of THF were mixed in a nitrogen atmosphere and cooled to −10° C.Thereafter, 2.7 g of potassium t-butoxide (t-BuOK) was added thereto bydividing into 3 portions at a temperature range of from −10 to −5° C.After stirring at −10° C. for 60 minutes, 7.0 g of the compound (7)dissolved in 14 mL of THF was added dropwise thereto at a temperaturerange of from −10 to −5° C. After stirring at 0° C. for 30 minutes, thereaction mixture was added to and mixed with a mixture of 100 mL ofwater and 50 mL of toluene, which was separated into an organic layerand an aqueous layer by standing still, so as to attain extraction tothe organic layer. The resulting organic layer was fractionated andwashed with water, followed by drying over anhydrous magnesium sulfate.A residue obtained by concentrating the resulting solution under reducedpressure was purified by silica gel column chromatography using a mixedsolvent of heptane and toluene (heptane/toluene=3/1 by volume) aseluent, and the eluate was concentrated under reduced pressure. Theresulting residue was purified by recrystallization from a mixed solventof heptane and Solmix A-11 (produced by Japan Alcohol Trading Co., Ltd.)(heptane/Solmix A-11=2/1 by volume) to obtain 5.6 g of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-vinylbicyclohexyl-3-ene (No.132) in white color. The yield based on the compound (7) was 80.3%.

The transition temperature (° C.) of the resulting compound (No. 132)was C 77.8 S_(A) 96.9 N 160.8 I.

The chemical shift δ (ppm) in ¹H-NMR analysis was as follows, and thusthe resulting compound was identified as4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-vinylbicyclo hexyl-3-ene. Thesolvent for measurement was CDCl₃. Chemical shift δ (ppm): 6.87 (td,1H), 6.65 (td, 1H), 5.91 (t, 1H), 5.81-5.75 (m, 1H), 4.96 (dt, 1H), 4.88(dt, 1H), 4.10 (q, 2H), 2.38-2.32 (m, 2H), 2.25-2.22 (m, 1H), 1.98-1.80(m, 7H), 1.47-1.31 (m, 5H), 1.14-1.03 (m, 5H).

Example 2 Synthesis of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propenylbicyclohexyl-3-ene (No.152)

10.2 g of well dried ethyltriphenylphosphonium bromide and 40 mL of THFwere mixed under nitrogen atmosphere and cooled to −10° C. Thereafter,3.0 g of potassium t-butoxide (t-BuOK) was added thereto by dividinginto 3 portions at a temperature range of from −10 to −5° C. Afterstirring at −10° C. for 60 minutes, 8.0 g of the compound (7) dissolvedin 16 mL of THF was added dropwise thereto at a temperature range offrom −10 to −5° C. After stirring at 0° C. for 30 minutes, the reactionmixture was added to and mixed with a mixture of 100 mL of water and 50mL of toluene, which was separated into an organic layer and an aqueouslayer by standing still, so as to attain extraction to the organiclayer. The resulting organic layer was fractionated and washed withwater, followed by drying over anhydrous magnesium sulfate. A residueobtained by concentrating the resulting solution under reduced pressurewas purified by silica gel column chromatography using a mixed solventof heptane and toluene (heptane/toluene=3/1 by volume) as eluent, andthe eluate was concentrated under reduced pressure to obtain 8.2 g of awhite solid matter. 32 mL of Solmix A-11 was added to 8.2 g of the whitesolid, to which, under stirring, 6.7 g of sodium benzenesulfinatedihydrate was added, and subsequently 10 mL of 6N hydrochloric acid wasadded, followed by refluxing under heating for 5 hours. After coolingthe reaction mixture to 30° C., 100 mL of water and 100 mL of toluenewere added to and mixed with the resulting solution. Thereafter, themixture was separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, a 0.5 Nsodium hydroxide aqueous solution, a saturated sodium bicarbonateaqueous solution, and water, followed by drying over anhydrous magnesiumsulfate. The resulting solution was concentrated under reduced pressure,and the resulting residue was purified by silica gel columnchromatography using a mixed solvent of heptane and toluene(heptane/toluene=3/1 by volume) as eluent, followed by concentrating theeluate under reduced pressure. The resulting residue was purified byrecrystallization from a mixed solvent of heptane and Solmix A-11(heptane/Solmix A-11=3/1 by volume) to obtain 1.37 g of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propenylbicyclohexyl-3-ene (No.152). The yield based on the compound (7) was 16.6%.

The transition temperature (° C.) of the resulting compound (No. 152)was C₁ 78.9 C₂ 83.4 N 201.1 I.

The chemical shift δ (ppm) in ¹H-NMR analysis was as follows, and thusthe resulting compound was identified as4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propenylbicyclohexyl-3-ene. Thesolvent for measurement was CDCl₃. Chemical shift δ (ppm): 6.87 (td,1H), 6.65 (td, 1H), 5.91 (t, 1H), 5.43-5.34 (m, 2H), 4.10 (q, 2H),2.43-2.32 (m, 2H), 2.25-2.21 (m, 1H), 1.97-1.73 (m, 7H), 1.64 (d, 3H),1.45-1.30 (m, 5H), 1.13-0.98 (m, 5H).

Example 3 Synthesis oftrans-4′-but-3-enyl-4-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3-ene(No. 172)

First Step: 29.5 g of well dried methoxymethyltriphenylphosphoniumchloride and 120 mL of THF were mixed under nitrogen atmosphere andcooled to −30° C. Thereafter, 9.7 g of potassium t-butoxide (t-BuOK) wasadded thereto by dividing into 4 portions at a temperature range of from−30 to −20° C. After stirring at −20° C. for 60 minutes, 25.0 g of thecompound (7) dissolved in 50 mL of THF was added dropwise thereto at atemperature range of from −20 to −10° C. After stirring at 0° C. for 30minutes, the reaction mixture was added to and mixed with a mixture of400 mL of water and 200 mL of toluene, which was separated into anorganic layer and an aqueous layer by standing still, so as to attainextraction to the organic layer. The resulting organic layer wasfractionated and washed with water, followed by drying over anhydrousmagnesium sulfate. A residue obtained by concentrating the resultingsolution under reduced pressure was purified by silica gel columnchromatography using a mixed solvent of heptane and toluene(heptane/toluene=7/3 by volume) as eluent. The resulting eluate wasconcentrated under reduced pressure to obtain 27.0 g of a pale yellowsolid. Subsequently, 27.0 g of the solid, 100 mL of toluene and 37.9 gof 87% formic acid were mixed and refluxed under heating for 3 hours.After cooling the reaction mixture to 30° C., 200 mL of water and 200 mLof toluene were added to and mixed with the resulting solution.Thereafter, the mixture was separated into an organic layer and anaqueous layer by standing still, so as to attain extraction to theorganic layer. The resulting organic layer was fractionated and washedwith water, a saturated sodium bicarbonate aqueous solution, and water,followed by drying over anhydrous magnesium sulfate. Thereafter, thesolvent was removed by distillation under reduced pressure, andresulting residue was purified by recrystallization from a mixed solventof heptane and THF (heptane/THF=2/1 by volume), followed by drying, toobtain 43.5 g of(4′-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3′-ene-trans-4-yl)acetaldehyde(8) in white color. The yield based on the compound (7) was 94.7%.

Second Step: 19.3 g of well dried methoxymethyltriphenylphosphoniumchloride and 80 mL of THF were mixed under nitrogen atmosphere andcooled to −25° C. Thereafter, 6.3 g of potassium t-butoxide (t-BuOK) wasadded thereto by dividing into 4 portions at a temperature range of from−25 to −15° C. After stirring at −20° C. for 60 minutes, 17.0 g of thecompound (8) dissolved in 40 mL of THF was added dropwise thereto at atemperature range of from −20 to −10° C. After stirring at 0° C. for 30minutes, the reaction mixture was added to and mixed with a mixture of200 mL of water and 100 mL of toluene, which was separated into anorganic layer and an aqueous layer by standing still, so as to attainextraction to the organic layer. The resulting organic layer wasfractionated and washed with water, followed by drying over anhydrousmagnesium sulfate. A residue obtained by concentrating the resultingsolution under reduced pressure was purified by silica gel columnchromatography using a mixed solvent of heptane and toluene(heptane/toluene=7/3 by volume) as eluent. The resulting eluate wasconcentrated under reduced pressure to obtain 19.1 g of a pale yellowsolid. Subsequently, 19.1 g of the solid, 100 mL of toluene and 25.9 gof 87% formic acid were mixed and refluxed under heating for 3 hours.After cooling the reaction mixture to 30° C., 200 mL of water and 200 mLof toluene were added to and mixed with the resulting solution, whichwas then separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, asaturated sodium bicarbonate aqueous solution, and water, followed bydrying over anhydrous magnesium sulfate. Thereafter, the solvent wasremoved by distillation under reduced pressure, and resulting residuewas purified by recrystallization from a mixed solvent of heptane andTHF (heptane/THF=2/1 by volume), followed by drying, to obtain 16.7 g of3-(4′-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3′-ene-trans-4-yl)propionaldehyde(9) in white color. The yield based on the compound (8) was 94.4%.

Third Step: 4.55 g of well dried methyltriphenylphosphonium bromide and20 mL of THF were mixed under nitrogen atmosphere and cooled to −10° C.Thereafter, 1.43 g of potassium t-butoxide (t-BuOK) was added thereto bydividing into 3 portions at a temperature range of from −10 to −5° C.After stirring at −5° C. for 60 minutes, 4.0 g of the compound (9)dissolved in 10 mL of THF was added dropwise thereto at a temperaturerange of from −10 to −5° C. After stirring at 0° C. for 30 minutes, thereaction mixture was added to and mixed with a mixture of 100 mL ofwater and 50 mL of toluene. Thereafter, the mixture was separated intoan organic layer and an aqueous layer by standing still, so as to attainextraction to the organic layer. The resulting organic layer wasfractionated and washed with water, followed by drying over anhydrousmagnesium sulfate. A residue obtained by concentrating the resultingsolution under reduced pressure was purified by silica gel columnchromatography using a mixed solvent of heptane and toluene(heptane/toluene=4/1 by volume) as eluent, and the eluate wasconcentrated under reduced pressure. The resulting residue was purifiedby recrystallization from a mixed solvent of heptane and Solmix A-11(heptane/Solmix A-11=2/1 by volume) to obtain 3.34 g oftrans-4′-but-3-enyl-4-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3-ene(No. 172). The yield based on the compound (9) was 84.0%.

The transition temperature (° C.) of the resulting compound (No. 172)was C 66.2 S_(A) 118.6N 174.1 I.

The chemical shift δ (ppm) in ¹H-NMR analysis was as follows, and thusthe resulting compound was identified astrans-4′-but-3-enyl-4-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3-ene.The solvent for measurement was CDCl₃. Chemical shift δ (ppm): 6.87 (td,1H), 6.65 (td, 1H), 5.91 (t, 1H), 5.86-5.78 (m, 1H), 5.00 (dd, 1H), 4.92(dd, 1H), 4.10 (q, 2H), 2.40-2.32 (m, 2H), 2.24-2.21 (m, 1H), 2.09-2.04(m, 2H), 1.97-1.88 (m, 2H), 1.83-1.75 (m, 4H), 1.46-1.26 (m, 7H),1.23-1.11 (m, 2H), 1.07-0.85 (m, 4H).

Example 4 Synthesis of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-pent-3-enylbicyclohexyl-3-ene(No. 192)

8.28 g of well dried ethyltriphenylphosphonium bromide and 40 mL of THFwere mixed under nitrogen atmosphere and cooled to −10° C. Thereafter,2.50 g of potassium t-butoxide (t-BuOK) was added thereto by dividinginto 3 portions at a temperature range of from −10 to −5° C. Afterstirring at −5° C. for 60 minutes, 7.00 g of the compound (9) dissolvedin 20 mL of THF was added dropwise thereto at −5° C. After stirring at0° C. for 30 minutes, the reaction mixture was added to and mixed with amixture of 100 mL of water and 100 mL of toluene. Thereafter, themixture was separated into an organic layer and an aqueous layer bystanding still so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with water, followedby drying over anhydrous magnesium sulfate. A residue obtained byconcentrating the resulting solution under reduced pressure was purifiedby silica gel column chromatography using a mixed solvent of heptane andtoluene (heptane/toluene=4/1 by volume) as eluent, and the eluate wasconcentrated under reduced pressure to obtain 7.77 g of a white solid.31 mL of Solmix A-11 was added to 7.77 g of the white solid, to which,under stirring, 12.0 g of sodium benzenesulfinate dihydrate was added,and subsequently 31 mL of 6N hydrochloric acid was added, followed byrefluxing under heating for 5 hours. After cooling the reaction mixtureto 30° C., 100 mL of water and 100 mL of toluene were added to and mixedwith the resulting solution, which was then separated into an organiclayer and an aqueous layer by standing still, so as to attain extractionto the organic layer. The resulting organic layer was fractionated andwashed with water, a 0.5N sodium hydroxide aqueous solution, a saturatedsodium bicarbonate aqueous solution and water, followed by drying overanhydrous magnesium sulfate. The resulting solution was concentratedunder reduced pressure, and the resulting residue was purified by silicagel column chromatography using a mixed solvent of heptane and toluene(heptane/toluene=3/1 by volume) as eluent, followed by concentrating theeluate under reduced pressure. The resulting residue was purified byrecrystallization from a mixed solvent of heptane and Solmix A-11(heptane/Solmix A-11=3/1 by volume) to obtain 1.50 g of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-pent-3-enylbicyclohexyl-3-ene(No. 192). The yield based on the compound (9) was 20.8%.

The transition temperature (° C.) of the resulting compound (No. 192)was C 64.4 S_(A) 123.7 N 189.3 I.

The chemical shift δ (ppm) in ¹H-NMR analysis was as follows, and thusthe resulting compound was identified as4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-pent-3-enylbicyclohexyl-3-ene.The solvent for measurement was CDCl₃. Chemical shift δ (ppm): 6.87 (td,1H), 6.65 (td, 1H), 5.91 (m, 1H), 5.46-5.37 (m, 2H), 4.10 (q, 2H),2.40-2.32 (m, 2H), 2.24-2.21 (m, 1H), 2.00-1.74 (m, 8H), 1.64 (d, 3H),1.45-1.30 (m, 5H), 1.27-1.10 (m, 4H), 1.06-0.84 (m, 4H).

Example 5 Synthesis of1-ethoxy-2,3-difluoro-4-(4-vinylcyclohex-1-enyl)benzene (No. 12)

First Step: 200.0 g of 1,4-dioxaspiro[4,5]decan-8-one (10), 301.4 g ofethyl diethylphosphonoacetate and 1,000 mL of toluene were added to areactor under nitrogen atmosphere, and stirred at 5° C. 457.5 g of a 20%sodium ethoxide ethanol solution was added dropwise thereto at atemperature range of from 5 to 11° C. over 2 hours, followed by furtherstirring at 10° C. for 3 hours. After confirming that the reaction hadbeen completed by GC analysis, the reaction mixture was poured into andmixed with 2,000 mL of water at 0° C. The mixture was separated into anorganic layer and an aqueous layer by standing still, so as to attainextraction to the organic layer. The resulting organic layer wasfractionated and washed with water, followed by drying over anhydrousmagnesium sulfate. Thereafter, the solvent was removed by distillationunder reduced pressure, and the resulting residue was purified by silicagel column chromatography using heptane as eluent, followed bydistilling the solvent off under reduced pressure, to obtain 267.3 g of(1,4-dioxaspiro[4.5]dec-8-ylidene)acetic acid ethyl ester (11) as a paleyellow liquid.

Second Step: 267.3 g of the compound (11), 5.0 g of Pd/C, 500 mL ofisopropyl alcohol (IPA) and 500 mL of toluene were added to a reactor,and stirred under hydrogen atmosphere for 24 hours. After confirmingthat the reaction had been completed by GC analysis, the Pd/C wasfiltered off, and the solvent was removed by distillation under reducedpressure to obtain a residue. The resulting residue was purified bysilica gel column chromatography using heptane as eluent, and thesolvent was distilled off under reduced pressure to obtain 255.2 g of(1,4-dioxaspiro[4,5]dec-8-yl)acetic acid ethyl ester (12) as a colorlessliquid.

Third Step: 20.0 g of lithium aluminum hydride (LAH) and 800 mL of THFwere added to a reactor under nitrogen atmosphere, and stirred at 3° C.190.0 g of the compound (12) dissolved in 200 mL of THF was addeddropwise thereto at a temperature range of from 0 to 7° C. over 2 hours,followed by further stirring at 0° C. for 3 hours. After confirming thatthe reaction had been completed by GC analysis, a mixture of 60 mL ofTHF and 60 mL of acetone was added dropwise thereto at 0° C. over 30minutes, and 100 mL of a 2N sodium hydroxide aqueous solution wasfurther added dropwise thereto at 10° C. over 30 minutes. A white solidthus deposited was filtered off, and 300 mL of toluene and 1,000 mL ofbrine were added to and mixed with the filtrate. The mixture wasseparated into an organic layer and an aqueous layer by standing still,so as to attain extraction to the organic layer. The resulting organiclayer was fractionated and washed with brine, followed by drying overanhydrous magnesium sulfate. Thereafter, the solvent was removed bydistillation under reduced pressure to obtain 152.7 g of2-(1,4-dioxaspiro[4,5]dec-8-yl)ethanol (13) as a colorless liquid.

Fourth Step: 150.0 g of the compound (13), 274.3 g of triphenylphosphine(Ph₃P), 71.3 g of imidazole and 900 mL of toluene were added to areactor under nitrogen atmosphere, and stirred at 3° C. 255.5 g ofiodine was added thereto by dividing into 10 portions at a temperaturerange of from 3 to 10° C., followed by further stirring at 0° C. for 3hours. After confirming that the reaction had been completed by GCanalysis, a yellow solid thus deposited was filtered off. The filtratewas concentrated, and 400 mL of heptane was added to the resultingresidue, followed by filtering off a pale yellow solid thus deposited.The filtrate was concentrated, and the resulting residue was purified bysilica gel column chromatography using toluene as eluent, and thesolvent was removed by distillation under reduced pressure to obtain223.9 g of 8-(2-iodoethyl)-1,4-dioxaspiro[4,5]decane (14) as a colorlesstransparent liquid.

Fifth Step: 223.0 g of the compound (14) and 800 mL of DMF were added toa reactor under nitrogen atmosphere, and stirred at 3° C. under coolingwith ice. 92.9 g of potassium t-butoxide (t-BuOK) was added thereto bydividing into 10 portions at a temperature range of from 3 to 10° C.,followed by further stirring at 0° C. for 3 hours. After confirming thatthe reaction had been completed by GC analysis, the reaction mixture waspoured into and mixed with a mixture of 1,500 mL of heptane and 1,500 mLof water at 0° C. The mixture was separated into an organic layer and anaqueous layer by standing still, so as to attain extraction to theorganic layer. The resulting organic layer was fractionated and washedwith water, followed by drying over anhydrous magnesium sulfate. Theresulting organic layer was purified by silica gel column chromatographyusing heptane as eluent, and the solvent was removed by distillationunder reduced pressure. The resulting residue was distilled underreduced pressure to obtain 103.3 g of 8-vinyl-1,4-dioxaspiro[4,5]decane(15) as a colorless transparent liquid.

Sixth Step: 103.3 g of the compound (15), 86.5 g of 98% formic acid and200 mL of toluene were added to a reactor in a nitrogen atmosphere, andstirred under refluxing and heating for 2 hours. After confirming thatthe reaction had been completed by GC analysis, the reaction mixture waspoured into and mixed with 500 mL of brine at 0° C. The mixture wasseparated into an organic layer and an aqueous layer by standing still,so as to attain extraction to the organic layer. The resulting organiclayer was fractionated and washed with a saturated sodium bicarbonateaqueous solution and brine, followed by drying over anhydrous magnesiumsulfate, and the solvent was removed by distillation under reducedpressure. The resulting residue was distilled under reduced pressure toobtain 66.7 g of 4-vinylcyclohexanone (16) as a colorless transparentliquid.

Seventh Step: 1.76 g of well dried magnesium and 10 mL of THF wereplaced in a reactor under nitrogen atmosphere, and heated to 53° C. 17.2g of the compound (1) dissolved in 30 mL of THF was slowly addeddropwise thereto at a temperature range of from 50 to 56° C., followedby stirring for 30 minutes. Thereafter, 6.0 g of the compound (16)dissolved in 10 mL of THF was slowly added dropwise thereto at atemperature range of from 50 to 55° C., followed by stirring for 30minutes. After cooling the resulting reaction mixture to 25° C., thereaction mixture was poured into and mixed with a mixture of 100 mL of1N hydrochloric acid and 100 mL of toluene. The mixture was thenseparated into an organic layer and an aqueous layer by standing still,so as to attain extraction to the organic layer. The resulting organiclayer was fractionated and washed with water, a 2N sodium hydroxideaqueous solution, a saturated sodium bicarbonate aqueous solution, andwater, followed by drying over anhydrous magnesium sulfate. Thereafter,the solvent was removed by distillation under reduced pressure to obtain18.5 g of 1-(4-ethoxy-2,3-difluorophenyl)-4-vinylcyclohexanol (17) as ayellow liquid.

Eighth Step: 18.5 g of the compound (17), 0.4 g of p-toluenesulfonicacid and 60 mL of toluene were mixed, and the mixture was refluxed underheating for 1 hour while water distilled out was removed. After coolingthe resulting reaction mixture to 25° C., 100 mL of water and 100 mL oftoluene were added to and mixed with the reaction mixture. Thereafter,the mixture was separated into an organic layer and an aqueous layer bystanding still, so as to attain extraction to the organic layer. Theresulting organic layer was fractionated and washed with a 2N sodiumhydroxide aqueous solution, a saturated sodium bicarbonate aqueoussolution and water, followed by drying over anhydrous magnesium sulfate.Thereafter, the solvent was removed by distillation under reducedpressure to obtain a residue. The resulting residue was purified bysilica gel column chromatography using a mixed solvent of heptane andtoluene (heptane/toluene=3/1 by volume) as eluent, and then furtherpurified by recrystallization from ethanol to obtain 2.58 g of1-ethoxy-2,3-difluoro-4-(4-vinylcyclohex-1-enyl)benzene (No. 12) inwhite color. The yield based on the compound (16) was 20.2%.

The transition temperature (° C.) of the resulting compound (No. 12) wasC 22.6 I.

The chemical shift δ (ppm) in ¹H-NMR analysis was as follows, and thusthe resulting compound was identified as1-ethoxy-2,3-difluoro-4-(4-vinylcyclohex-1-enyl)benzene. The solvent formeasurement was CDCl₃. Chemical shift δ (ppm): 6.85 (td, 1H), 6.64 (td,1H), 5.90-5.83 (m, 2H), 5.05 (dt, 1H), 4.97 (dt, 1H), 4.08 (q, 2H),2.48-2.27 (m, 4H), 2.06-2.00 (m, 1H), 1.93-1.88 (m, 1H), 1.56-1.49 (m,1H), 1.42 (t, 3H).

Example 6

Compounds (No. 1) to (No. 360) can be synthesized by methods similar tothe synthesis methods described in Examples 1 to 5. The data attached tothe compounds are those measured in the methods described above. Thevalues of transition temperature are values obtained by measuring thecompounds themselves, and the values of maximum temperature (T_(NI)),dielectric anisotropy (Δ∈) and optical anisotropy (Δn) are extrapolatedvalues obtained by converting measured values of samples mixed with thebase mixtures (i) according to the aforementioned extrapolation method.

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Comparative Example 1

As a comparative example,trans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-ethylbicyclohexyl (F) wassynthesized, in which the compound had alkyl instead of alkenyl, and hadcyclohexyl instead of cyclohexenyl.

The five compounds described for the base mixtures (i) were mixed toprepare base mixtures (i) having a nematic phase. The base mixtures (i)had the following properties:

Maximum temperature (T_(NI)) 74.0° C. Optical anisotropy (Δn)   0.087Dielectric anisotropy (Δε) −1.3 Viscosity (η₂₀) 18.9 mPa · s

A liquid crystal composition (ii) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-ethylbicyclohexyl (F)thus synthesized was prepared. The resulting liquid crystal composition(ii) was measured for properties, and the extrapolated values of theproperties of the comparative compound (F) were calculated byextrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 129.3° C. Optical anisotropy (Δn)   0.105Dielectric anisotropy (Δε) −5.92 Viscosity (η) 46.2 mPa · s

The liquid crystal composition (ii) had an elastic constant K₃₃ of 15.58pN. After storing the liquid crystal composition (ii) in a freezer at−10° C. for 30 days, the liquid crystal composition (ii) wascrystallized.

Comparative Example 2

As a comparative example,trans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-vinylbicyclohexyl (G) wassynthesized, in which the compound had alkenyl, and had cyclohexylinstead of cyclohexenylene.

A liquid crystal composition (iii) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-vinylbicyclohexyl (G)thus synthesized was prepared. The resulting liquid crystal composition(iii) was measured for properties, and the extrapolated values of theproperties of the comparative compound (G) were calculated byextrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 141.9° C. Optical anisotropy (Δn)   0.111Dielectric anisotropy (Δε) −5.59 Viscosity (η) 38.5 mPa · s

The liquid crystal composition (iii) had an elastic constant K₃₃ of15.15 pN.

Comparative Example 3

As a comparative example,trans-4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-ethyl bicyclohexyl-3-ene(H), in which the compound had alkenyl, and had cyclohexyl instead ofcyclohexenylene.

A liquid crystal composition (iv) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-ethylbicyclohexyl-3-ene(H) thus synthesized was prepared. The resulting liquid crystalcomposition (iv) was measured for properties, and the extrapolatedvalues of the properties of the comparative compound (H) were calculatedby extrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 132.6° C. Optical anisotropy (Δn)   0.128Dielectric anisotropy (Δε) −6.1 Viscosity (η) 47.7 mPa · s

The liquid crystal composition (iv) had an elastic constant K₃₃ of 15.2pN. After storing the liquid crystal composition (iv) in a freezer at−10° C. for 30 days, the liquid crystal composition (iv) wascrystallized.

Example 7 Properties of Liquid Crystal Compound (No. 132)

A liquid crystal composition (v) including 85% by weight of the basemixtures (i) and 15% by weight of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-vinylbicyclohexyl-3-ene (No.132) obtained in Example 1 was prepared. The resulting liquid crystalcomposition (v) was measured for properties, and the extrapolated valuesof the properties of the liquid crystal compound (No. 132) werecalculated by extrapolating the measured values. The values thusobtained were as follows:

Maximum temperature (T_(NI)) 143.9° C. Optical anisotropy (Δn)   0.141Dielectric anisotropy (Δε) −6.03 Viscosity (η) 38.7 mPa · s

The liquid crystal composition (v) had an elastic constant K₃₃ of 16.12pN. After storing the liquid crystal composition (v) in a freezer at−10° C. for 30 days, the liquid crystal composition (v) maintained anematic phase.

It was understood from the results that the liquid crystal compound (No.132) had a high maximum temperature (T_(NI)), a large optical anisotropy(Δn) and a negatively large dielectric anisotropy (Δ∈), and hadexcellent compatibility with other liquid crystal compounds at a lowtemperature.

It was also understood that the liquid crystal compound (No. 132) had adielectric anisotropy (Δ∈) that was equivalent to the comparativecompounds (F) and (H), but had a higher maximum temperature (T_(NI)) ofnematic phase, a smaller viscosity (η) and a larger optical anisotropy(Δn) and an elastic constand K₃₃ than the comparative compounds (F) and(H).

It was also understood that the liquid crystal compound (No. 132) had amaximum temperature (T_(NI)) of nematic phase and a viscosity (η) thatwere equivalent to the comparative compound (G), but had a negativelylarge dielectric anisotropy, a larger optical anisotropy (Δn) and alarger elastic constant K₃₃ than the comparative compound (G).

Comparative Example 4

As a comparative example,trans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-propylbicyclohexyl (I)was synthesized, in which the compound had alkyl instead of alkenyl, andhad cyclohexyl instead of cyclohexenyl.

A liquid crystal composition (vi) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-propylbicyclohexyl (I)thus synthesized was prepared. The resulting liquid crystal composition(vi) was measured for properties, and the extrapolated values of theproperties of the comparative compound (I) were calculated byextrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 159.9° C. Optical anisotropy (Δn)   0.112Dielectric anisotropy (Δε) −5.32 Viscosity (η) 41.0 mPa · s

After storing the liquid crystal composition (vi) in a freezer at −10°C. for 30 days, the liquid crystal composition (vi) was crystallized.

Comparative Example 5

As a comparative example,trans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-propenylbicyclohexyl (J)was synthesized, in which the compound had alkenyl, and had cyclohexylinstead of cyclohexenylene.

A liquid crystal composition (vii) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4′-(4-ethoxy-2,3-difluorophenyl)-trans-4-propenylbicyclohexyl (J)thus synthesized was prepared. The resulting liquid crystal composition(vii) was measured for properties, and the extrapolated values of theproperties of the comparative compound (J) were calculated byextrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 175.3° C. Optical anisotropy (Δn)   0.132Dielectric anisotropy (Δε) −5.44 Viscosity (η) 44.8 mPa · s

After storing the liquid crystal composition (vii) in a freezer at −10°C. for 30 days, the liquid crystal composition (vii) was crystallized.

Comparative Example 6

As a comparative example,trans-4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propylbicyclohexyl-3-ene(K), in which the compound had alkenyl, and had cyclohexyl instead ofcyclohexenylene.

A liquid crystal composition (viii) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propylbicyclohexyl-3-ene(K) thus synthesized was prepared. The resulting liquid crystalcomposition (viii) was measured for properties, and the extrapolatedvalues of the properties of the comparative compound (K) were calculatedby extrapolating the measured values. The values thus obtained were asfollows:

Maximum temperature (T_(NI)) 157.3° C. Optical anisotropy (Δn)   0.140Dielectric anisotropy (Δε) −6.28 Viscosity (η) 37.8 mPa · s

After storing the liquid crystal composition (viii) in a freezer at −10°C. for 30 days, the liquid crystal composition (viii) was crystallized.

Example 8 Properties of Liquid Crystal Compound (No. 152)

A liquid crystal composition (ix) including 85% by weight of the basemixtures (i) and 15% by weight of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-propenyl-bicyclohexyl-3-ene(No. 152) obtained in Example 2 was prepared. The resulting liquidcrystal composition (ix) was measured for properties, and theextrapolated values of the properties of the liquid crystal compound(No. 152) were calculated by extrapolating the measured values. Thevalues thus obtained were as follows:

Maximum temperature (T_(NI)) 173.3° C. Optical anisotropy (Δn)   0.164Dielectric anisotropy (Δε) −6.48 Viscosity (η) 42.59 mPa · s

It was understood from the results that the liquid crystal compound (No.152) had a high maximum temperature (T_(NI)), a large optical anisotropy(Δn) and a large negative dielectric anisotropy (Δ∈).

It was also understood that the liquid crystal compound (No. 152) had ahigher maximum temperature (T_(NI)), a large negative dielectricanisotropy (Δ∈) and a large optical anisotropy (Δn) than the comparativecompounds (I) and (K).

It was also understood that the liquid crystal compound (No. 152) had amaximum temperature (T_(NI)) and a viscosity (η) that were equivalent tothe comparative compound (J), but had a larger negative dielectricanisotropy (Δ∈) and a larger optical anisotropy (Δn) than thecomparative compound (J).

Example 9 Low Temperature Compatibility of Liquid Crystal Compound (No.172)

A liquid crystal composition (x) including 85% by weight of the basemixtures (i) and 15% by weight oftrans-4′-but-3-enyl-4-(4-ethoxy-2,3-difluorophenyl)-bicyclohexyl-3-ene(No. 172) described in Example 6 was prepared. The liquid crystalcomposition (x) was stored in a freezer at −10° C. for 30 days, and theliquid crystal composition (x) maintained a nematic phase. It wasunderstood from the results that the liquid crystal compound (No. 172)had excellent compatibility with other liquid crystal compounds at a lowtemperature.

Example 10 Low Temperature Compatibility of Liquid Crystal Compound (No.212)

A liquid crystal composition (xi) including 85% by weight of the basemixtures (i) and 15% by weight of4-(4-ethoxy-2,3-difluorophenyl)-trans-4′-pent-4-enyl-bicyclohexyl-3-ene(No. 212) described in Example 6 was prepared. The liquid crystalcomposition (xi) was stored in a freezer at −10° C. for 30 days, and theliquid crystal composition (xi) maintained a nematic phase. It wasunderstood from the results that the liquid crystal compound (No. 212)had excellent compatibility with other liquid crystal compounds at a lowtemperature.

Examples of Liquid Crystal Composition

The invention will be explained in detail by way of Examples. Thecompounds used in the Examples are expressed by the symbols according tothe definition in Table 1. In Table 1, the configuration of1,4-cyclohexylene is trans. The ratios (percentages) of the liquidcrystal compounds are percentages by weight (% by weight) based on totalweight of the liquid crystal composition. The characteristics of thecomposition are shown at the last of the Examples.

The numbers next to the liquid crystal compounds used in the Examplescorrespond to the number of the liquid crystal compounds used as thefirst to third components of the invention.

A method of description of compounds using symbols is shown below.

TABLE 1 Method of Description of Compound using Symbols.R—(A₁)—Z₁— - - - —Z_(n)—(A_(n))—R′ Symbol 1) Left Terminal Group R—C_(n)H_(2n+1)— n- C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-C_(n)H_(2n+1)CH═CH— nV- CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)CH═CHC_(n)H_(2n)— mVn- 2) Ring Structure —A_(n)—

Ch

B

B(3F)

B(2F,3F)

H 3) Bonding group —Z_(n)— —C₂H₄— 2 —CH₂O— 1O —OCH₂— O1 —COO— E —OCO— Er4) Right Terminal Group —R′ —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) -On—C_(n)H_(2n)OC_(m)H_(2m+1) -nOm —CH═CH₂ -V —CH═CHC_(n)H_(2n+1) -Vn—C_(n)H_(2n)CH═CHC_(m)H_(2m+1) -nVm 5) Example of Description Example 1V-HCh(2F,3F)-O1

Example 2 V-HHB-1

Example 3 1V-Ch(2F,3F)-O2

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectric Industries Association of Japan, EIAJ•ED-2521 A or those withsome modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point measuring apparatus equipped with apolarizing microscope and was heated at the rate of 1° C. per minute.The temperature was measured when a part of the sample began to changefrom a nematic phase into an isotropic liquid. A higher limit of atemperature range of a nematic phase may be abbreviated to “a maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was stored in a freezer at temperatures of 0° C., −10° C.,−20° C., −30° C. and −40° C. for ten days, respectively, and a liquidcrystal phase was observed. For example, when the sample remained in anematic phase at −20° C. and changed to crystals or a smectic phase at−30° C., Tc was expressed as ≦−20° C. A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”

Optical Anisotropy (Δn; measured at 25° C.): Measurement was carried outwith an Abbe refractometer mounting a polarizing plate on an ocularusing a light at a wavelength of 589 nm. The surface of a main prism wasrubbed in one direction, and then a sample was dropped on the mainprism. The refractive index (n∥) where the direction of a polarizedlight was parallel to that of the rubbing and a refractive index (n⊥)where the direction of a polarized light was perpendicular to that ofthe rubbing were measured. The value of optical anisotropy (Δn) wascalculated from the equation: (Δn)=(n∥)−(n⊥).

Viscosity (η; measured at 20° C.; mPa·s): The viscosity was measured bymeans of an E-type viscometer.

Dielectric Anisotropy (Δ∈; measured at 25° C.): A solution ofoctadecyltriethoxysilane (0.16 mL) dissolved in ethanol (20 mL) wascoated on a glass substrate having been well cleaned. The glasssubstrate was rotated with a spinner and then heated to 150° C. for 1hour. A VA device having a distance (cell gap) of 20 μm was fabricatedwith two glass substrates. A polyimide orientation film was prepared ona glass substrate in the same manner. The resulting orientation film onthe glass substrate was subjected to a rubbing treatment, and then a TNdevice having a distance between two glass substrates of 9 μm and atwist angle of 80° was fabricated. A sample (a liquid crystalcomposition or a mixture of a liquid crystal composition and basemixtures) was charged in the VA device, and sine waves (0.5 V, 1 kHz)were applied to the device to measure a dielectric constant (∈∥) in themajor axis direction of the liquid crystal molecule. A sample (a liquidcrystal composition or a mixture of a liquid crystal composition andbase mixtures) was charged in the TN device, and sine waves (0.5 V, 1kHz) were applied to the device to measure a dielectric constant (∈⊥) inthe minor axis direction of the liquid crystal molecule. The value of adielectric anisotropy was calculated from the equation: Δ∈=∈∥−∈⊥.

Voltage Holding Ratio (VHR; measured at 25° C. and 100° C.; %): A samplewas charged to a cell having a polyimide orientation film and a distance(cell gap) between two glass substrate of 6 μm to fabricate a TN device.The TN device was applied and charged with pulse voltage (60microseconds at 5 V). The waveform of the voltage applied to the TNdevice was observed with cathode ray oscilloscope, and an area betweenthe voltage curve and the horizontal axis in a unit cycle (16.7milliseconds) was obtained. The area was similarly obtained from thewaveform of the voltage applied after removing the TN device. The valueof a voltage holding ratio (%) was calculated from the equation:(voltage holding ratio)=(area with TN device)/(area without TNdevice)×100.

The voltage holding ratio thus obtained is expressed as “VHR-1.” The TNdevice was then heated to 100° C. for 250 hours. The TN device wascooled to 25° C., and then the voltage holding ratio was measured in thesame manner as above. The voltage holding ratio obtained afterconducting the heating test is expressed as “VHR-2.” The heating test isan accelerating test used as a test corresponding to a long-termdurability test of a TN device.

Example 11

V-ChB(2F,3F)-1 (No. 1) 10% V-ChB(2F,3F)-O2 (No. 12) 11% V-ChB(2F,3F)-O4(No. 14) 11% V-HChB(2F,3F)-1 (No. 121) 10% V-HChB(2F,3F)-O2 (No. 132)10% V-HChB(2F,3F)-O4 (No. 134) 11% 2-HH-5 (2-1) 10% 3-HB-O2 (2-4) 15%3-HHEBH-3 (2-74) 7% 3-HHEBH-5 (2-74) 5%

NI=76.4° C.; Tc≦−20° C.; Δn=0.100; η=21.1 mPa·s; Δ∈=−3.2.

Example 12

1V-ChB(2F,3F)-1 (No. 21) 12% 1V-ChB(2F,3F)-O2 (No. 32) 12%1V-ChB(2F,3F)-O4 (No. 34) 12% 1V-HChB(2F,3F)-O2 (No. 152) 10%1V-HChB(2F,3F)-O4 (No. 154) 10% 3-HH-4 (2-1) 10% 3-HB-O2 (2-4) 16%3-HHEH-3 (2-46) 5% 3-HHEH-5 (2-46) 5% 5-HBB(3F)B-2 (2-73) 8%

NI=84.2° C.; Δn=0.113; η=25.8 mPa·s; Δ∈=−3.0.

Example 13

V-ChB(2F,3F)-O2 (No. 12) 11% V-ChB(2F,3F)-O4 (No. 14) 11%1V-ChB(2F,3F)-O2 (No. 32) 11% V-HChB(2F,3F)-1 (No. 121) 10%V-HChB(2F,3F)-O2 (No. 132) 8% V-HChB(2F,3F)-O4 (No. 134) 7%1V-HChB(2F,3F)-O2 (No. 152) 8% 1V-HChB(2F,3F)-O4 (No. 154) 7% 5-HH-V(2-1) 22% V-HHB-1 (2-25) 5%

NI=74.1° C.; Δn=0.102; η=21.4 mPa·s; Δ∈=−4.0.

Example 14

V-ChB(2F,3F)-O4 (No. 14) 10% 1V-ChB(2F,3F)-O2 (No. 32) 10%1V-ChB(2F,3F)-O4 (No. 34) 10% V-HChB(2F,3F)-O2 (No. 132) 10%V-HChB(2F,3F)-O4 (No. 134) 10% 3-HH-V1 (2-1) 10% 3-HH-O1 (2-1) 10%V-HHB-1 (2-25) 5% 3-HHB-O1 (2-25) 5% 3-HBB-2 (2-35) 5% 2-BB(3F)B-3(2-44) 5% 2-BB(3F)B-5 (2-44) 5% V2-BB(3F)B-1 (2-44) 5%

NI=79.3° C.; Δn=0.126; η=22.1 mPa·s; Δ∈=−3.0.

Example 15

V-ChB(2F,3F)-O2 (No. 12) 10% 1V-ChB(2F,3F)-O2 (No. 32) 10%1V-ChB(2F,3F)-O4 (No. 34) 10% V-HChB(2F,3F)-O2 (No. 132) 10%V-HChB(2F,3F)-O4 (No. 134) 10% 1V-HChB(2F,3F)-O2 (No. 152) 10% 3-HH-O1(2-1) 10% 5-HB-3 (2-4) 5% 3-HB-O1 (2-4) 10% 3-HHB-1 (2-25) 5% 3-HHEH-3(2-46) 5% 3-HHEBH-3 (2-74) 5%

NI=77.6° C.; Δn=0.099; η=24.7 mPa·s; Δ∈=−3.5.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal compound comprising a compound selected from a groupof compounds represented by formula (a):

wherein Ra and Rb are each independently hydrogen, alkyl having 1 to 10carbons or alkenyl having 2 to 10 carbons, provided that in the alkyl,—CH₂— may be replaced by —O—, but plural —O— are not adjacent to eachother, and hydrogen may be replaced by fluorine; ring A¹ and ring A² areeach independently trans-1,4-cyclohexylene or 1,4-phenylene, providedthat one or two hydrogens of the 1,4-phenylene may be replaced byhalogen, and in a 6-membered ring of these groups, one —CH₂— or two—CH₂— that are not adjacent to each other may be replaced by —O—, andone or two —CH═ may be replaced by —N═; Z¹ and Z² are each independentlya single bond, —(CH₂)₂—, —(CH₂)₄—, —CH═CH—, —C≡C—, —CH₂O—, —OCH₂—,—COO—, —OCO— or —OCF₂—; l and m are each independently 0, 1 or 2,provided that l+m is 0, 1, 2 or 3; and n is an integer of from 0 to 6,provided that in —(CH₂)_(n)—, —CH₂— may be replaced by —O—, but plural—O— are not adjacent to each other, and hydrogen may be replaced byfluorine.
 2. The liquid crystal compound according to claim 1, whereinring A¹, ring A² and ring A³ are each independentlytrans-1,4-cyclohexylene or 1,4-phenylene; Z¹ and Z² are each a singlebond; and l+m is 0 or 1; and n is an integer of from 0 to
 6. 3. Theliquid crystal compound according to claim 2, wherein Ra is hydrogen oralkyl having 1 to 10 carbons; and Rb is alkoxy having 1 to 9 carbons. 4.The liquid crystal compound according to claim 3, wherein l+m is
 1. 5. Aliquid crystal composition comprising at least one compound according toclaim
 1. 6. A liquid crystal composition having a negative dielectricanisotropy comprising two components, wherein the first component is atleast one compound according to claim 1, and the second component is atleast one compound selected from the group of compounds represented byformulae (e-1), (e-2) and (e-3):

wherein Ra₁₁ and Rb₁₁ are each independently alkyl having 1 to 10carbons, provided that in the alkyl, —CH₂— that are not adjacent to eachother may be replaced by —O—, —(CH₂)₂— that are not adjacent to eachother may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴ are eachindependently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and Z¹¹, Z¹² and Z¹³are each independently a single bond, —CH₂—CH₂—, —CH═CH—, —C≡C—, —COO—or —CH₂O—.
 7. A liquid crystal composition having a negative dielectricanisotropy comprising two components, wherein the first component is atleast one compound according to claim 3, and the second component is atleast one compound selected from a group of compounds represented byformulae (e-1), (e-2) and (e-3):

wherein Ra₁₁ and Rb₁₁ are each independently alkyl having 1 to 10carbons, provided that in the alkyl, —CH₂— that are not adjacent to eachother may be replaced by —O—, —(CH₂)₂— that are not adjacent to eachother may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴ are eachindependently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and Z¹¹, Z¹² and Z¹³are each independently a single bond, —CH₂—CH₂—, —CH═CH—, —C≡C—, —COO—or —CH₂O—.
 8. The liquid crystal composition according to claim 7,wherein the ratio of the first component is from approximately 30% toapproximately 85% by weight, and the ratio of the second component isfrom approximately 15% to approximately 70% by weight, based on thetotal weight of the liquid crystal composition.
 9. The liquid crystalcomposition according to claim 6, wherein the liquid crystal compositionfurther comprises at least one compound selected from the group ofcompounds represented by formulae (g-1), (g-2), (g-3) and (g-4) as athird component:

wherein Ra₂₁ and Rb₂₁ are each independently hydrogen or alkyl having 1to 10 carbons, provided that in the alkyl, —CH₂— that are not adjacentto each other may be replaced by —O—, —(CH₂)₂— that are not adjacent toeach other may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A²¹, ring A²² and ring A²³ are each independentlytrans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; Z²¹, Z²² and Z²³ areeach independently a single bond, —CH₂C—CH₂—, —CH═CH—, —C≡—, —OCF₂—,—CF₂O—, —OCF₂CH₂CH₂—, —CH₂CH₂CF₂O—, —COO—, —OCO—, —OCH₂— or —CH₂O—; Y¹,Y², Y³ and Y⁴ are each independently fluorine or chlorine; and q, r ands are each independently 0, 1 or 2, provided that q+r+s is 1, 2 or 3,and t is 0, 1 or
 2. 10. The liquid crystal composition according toclaim 9, wherein the third component is at least one compound selectedfrom a group of compounds represented by formulae (h-1), (h-2), (h-3),(h-4) and (h-5):

wherein Ra₂₂ is linear alkyl having 1 to 8 carbons or linear alkenylhaving 2 to 8 carbons; Rb₂₂ is linear alkyl having 1 to 8 carbons,linear alkenyl having 2 to 8 carbons or alkoxy having 1 to 7 carbons;Z²⁴ is a single bond or —CH₂CH₂—; and both Y¹ and Y² are fluorine, orone of Y¹ and Y² is fluorine, and the other is chlorine.
 11. A liquidcrystal composition having a negative dielectric anisotropy comprisingthree components, wherein the first component is at least one compoundaccording to claim 3, the second component is at least one compoundselected from the group of compounds represented by formulae (e-1),(e-2) and (e-3):

wherein Ra₁₁ and Rb₁₁ are each independently alkyl having 1 to 10carbons, provided that in the alkyl, —CH₂— that are not adjacent to eachother may be replaced by —O—, —(CH₂)₂— that are not adjacent to eachother may be replaced by —CH═CH—, and hydrogen may be replaced byfluorine; ring A¹¹, ring A¹², ring A¹³ and ring A¹⁴ are eachindependently trans-1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl,1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and Z¹¹, Z¹² and Z¹³are each independently a single bond, —CH₂—CH₂—, —CH═CH—, —C≡C—, —COO—or —CH₂O—; and the third component is at least one compound selectedfrom the group of compounds represented by formulae (h-1), (h-2), (h-3),(h-4) and (h-5):

wherein Ra₂₂ is linear alkyl having 1 to 8 carbons or linear alkenylhaving 2 to 8 carbons; Rb₂₂ is linear alkyl having 1 to 8 carbons,linear alkenyl having 2 to 8 carbons or alkoxy having 1 to 7 carbons;Z²⁴ is a single bond or —CH₂CH₂—; and both Y¹ and Y² are fluorine, orone of Y¹ and Y² is fluorine, and the other is chlorine.
 12. The liquidcrystal composition according to claim 11, wherein the ratio of thefirst component is from approximately 10 to approximately 80% by weight,the ratio of the second component is from approximately 10% toapproximately 80% by weight, and the ratio of the third component isfrom approximately 10% to approximately 80% by weight, based on thetotal weight of the liquid crystal composition.
 13. The liquid crystalcomposition according to claim 11, wherein the liquid crystalcomposition further comprises at least one of an antioxidant and anultraviolet light absorbent.
 14. The liquid crystal compositionaccording to claim 13, wherein the antioxidant is at least oneantioxidant represented by formula (I):

wherein w is an integer of 1 to
 15. 15. A liquid display devicecomprising the liquid crystal composition according to claim
 5. 16. Aliquid display device comprising the liquid crystal compositionaccording to claim
 7. 17. The liquid crystal display device according toclaim 15, wherein the liquid crystal display device has an operationmode of a VA mode or an IPS mode, and has a driving mode of an activematrix mode.
 18. The liquid crystal display device according to claim16, wherein the liquid crystal display device has an operation mode of aVA mode or an IPS mode, and has a driving mode of an active matrix mode.